yashsingh1/xdaforums huggingface dataset:
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] retiredtab:
Glad you got it working.

Since I don't have a BOE panel, this is just my analysis, but I don't think TWRP is the problem here. I suspect the problem is with the Samsung stock bootloader not passing the BOE panel parameter to the kernel that TWRP and the custom ROMs use.

The TWRP that spiramedia links to is TWRP 3.3.1 as shown in his pictures. It's the same TWRP I use. There's nothing special about 3.3.1 with respect to BOE.

As you can see in post #29

https://xdaforums.com/showpost.php?p=83787085&postcount=29

the kernel is being passed the

mdss_mdp.panel=1:dsi:0:ss_dsi_panel_S6D7AA0_LSL080AL03_BOE_WXGA:1:none

BOE parameter. The bootloader is "androidboot.bootloader=T350XXU1BPI2". It's possible that other stock Samsung bootloaders have a bug in it that doesn't properly pass the BOE parameter to the kernel in TWRP and custom rom so it can load the proper BOE driver which leaves the backlight off.

Again, I don't have a BOE panel and it's just my analysis based on what I read and what others reported.

---------- Post added at 11:30 AM ---------- Previous post was at 11:26 AM ----------

BTW, I built that above 16.0 image. Any reason you loaded 16.0 vs 17.1? I don't plan on building any more 16.0 images. I already build the SM-T350, SM-T560NU and possibly the SM-P550. It's too much work to build both 16.0 and 17.1 for all 3 platforms so I settled on 17.1. All the 17.1 images get monthly security patches as they become available from the lineageos team.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] lpedia:
To answer the last comment first: there was no particular reason to go to 16.0, and I will be flashing your 17.1 later today. 16.0 was just a ROM I used it to check that TWRP 3.3.1 would actually accept and install it. I'd had two major issues: (1) all but one TWRP booting with blank screen; (2) the one non-blank TWRP refusing to flash any ROMs. Having got past (1) to a visible TWRP screen, in wild elation I just tested (2) with the first ROM I laid hands on. It was getting late at night here. :)

About where the real problem is, and TWRP versions: thank you for the clarification. I had assumed TWRP could be doing something wrong only because I'd tried at least half a dozen different versions and just

one

- ashyx's twrp_3.1.1-1_sm-t355_251117 - doesn't blank the screen (but it also wouldn't flash system ROMs).

About TWRP 3.3.1 - I wasn't sure that the TWRP from spiramedia's Yandex link was the same as your 3.3.1, because the file is actually named twrp_3.3.0-1_sm-t350.tar. I did see that it says 3.3.1 when it boots, but I'd earlier tried 3.3.1 without success, so thought they might be different.

I can do some testing to see if other stock bootloaders work. Some posts on other threads have reported that only starting from stock Marshmallow works (different T350 issues, not necessarily blank screen, and without identifying a specific Marshmallow ROM). Maybe Nougat is where the BOE issue started.

I have two identical T350s, and haven't updated the second one yet. I will try a few different stock ROMs on it and have a look at the parameters.

Once again, my thanks! :)
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] retiredtab:
The one TWRP that worked with BOE might have

1) using a prebuilt stock kernel that already defaulted to BOE on the kernel command line

2) built from sources, but with BOE defined on the kernel command line by whoever built it

3) the 355 tablet might only have BOE sourced panels and uses #1 or #2 above

The reason the older TWRP didn't flash the newer roms is because of the assert statement. It's job is to check whether you are flashing the right rom on the right tablet. It's easy to bypass by commenting out the assert statements in the zip rom file.

Do an adb shell then

cat /proc/cmdline

I suspect the aboot.mbn partition inside the stock rom zips is where the bootloader is. When I do a vi aboot.mbn, I can see the androidboot.bootloader=T350XXU1BPI2 inside that file.

So in theory, all you need to do is get the aboot.mbn partition file from the zip and do a

heimdall flash --aboot aboot.mbn

Please note, I don't have the BOE and have not tried the above command. If you are using odin to the flash the entire stock rom, odin will flash the aboot automatically. The aboot.mbn is 1MB in size and it would be a lot faster than downloading a 1.4GB stock rom zip file just to get the working BOE bootloader. It also would be a lot easier just to type in the one command above (assuming it works).

=== output to show aboot partition ===

gt58wifi:/dev/block/platform/soc.0/7824900.sdhci/by-name # ls -al

lrwxrwxrwx 1 root root 20 1971-07-20 06:53 aboot -> /dev/block/mmcblk0p5
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] lpedia:
Sounds reasonable. :) I'm not quite up to tinkering with a ROM zip file yet, though.

True, it would be quicker to flash just the stock bootloader rather than the whole thing. Tried T350XXU1BQA1 (another stock 6.0.1), but it didn't turn on TWRP backlight. I didn't check /proc/cmdline because I couldn't reboot system - it got into a boot loop. I had followed the only instructions I could find online about installing bootloader alone with Odin, and those might not have been correct.

Will test with the full (stock) ROM on the second T350 later. I've just installed lineage-17.1-20201108-UNOFFICIAL-gt58wifi.zip on the first one, and it 's looking good. :)

I'm willing to be a tester for T350 with BOE, if you need one.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] lpedia:
Tested by flashing full stock T350XXU1BQA1 ROM and TWRP 3.3.1, and the display was blank when TWRP booted. Then flashed T350XXU1BPI2 and TWRP 3.3.1 again, and it worked.

So ... it's not just any old 6.0.1 bootloader that'll do the trick. The T350XXU1BPI2 bootloader will. Maybe other stock MM ROMs released before BQA1 would, too.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] retiredtab:
According to

https://www.sammobile.com/samsung/galaxy-tab-a/firmware/#SM-T350

T350XXU1BPI2, it's the Canadian bootloader. ;) :highfive:

One working bootloader for BOE panels is all that is needed for now.

Now if you can try just flashing the aboot.mbn partition with T350XXU1BPI2, then we know that a single 1MB file will help BOE panels.

heimdall is at

https://www.glassechidna.com.au/heimdall/

I run Lubuntu, not windows, but heimdall is what I use for flashing.

---------- Post added at 08:01 PM ---------- Previous post was at 07:51 PM ----------

No rush, but can you post the 1MB file aboot.mbn from each rom zip? I just want to view via hexeditor and compare the two. You can zip it and post it here since they allow 20MB zip files.

Thanks.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] lpedia:
Agreed that we only need one. :)

I'll try the aboot.mbn flash later today.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] retiredtab:
Don't forget to flash both. Flash the non working one first to verify that you have no backlight, then the working one after.

Make sure your tablet isn't low on battery (suggest > 50%) because there's always a danger of a bricked device when flashing.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] lpedia:
Here you go ... if my first attempt at attaching a file has worked. :)
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] lpedia:
Thanks - yes, I had planned to test both :) and always have devices well-charged when tinkering with them. Haven't bricked one yet, but there is always a first time. ;)
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] retiredtab:
My speculation looks to be correct with respect to above.

After looking at both aboot.mbn files from T350XXU1BQA1 and T350XXU1BPI2, the BQA1 shows "ss_dsi_panel_LSL080AL03_BOE_WXGA" while BPI2 shows "ss_dsi_panel_S6D7AA0_LSL080AL03_BOE_WXGA".

So the non working BQA1 is missing the string S6D7AA0.

In the linux kernel code at

kernel/samsung/msm8916/arch/arm/configs/msm8916_sec_gt58wifi_eur_defconfig

#LCD

CONFIG_PANEL_S6D7AA0_LSL080AL03_WXGA=y

CONFIG_PANEL_S6D7AA0_LSL080AL03_BOE_WXGA=y

the kernel expects it to be defined with the S6D7AA0. So BQA1 is probably just passing

mdss_mdp.panel=1:dsi:0:ss_dsi_panel_LSL080AL03_BOE_WXGA:1:none

to the kernel and since there are no matching drivers for it, the kernel never turns on the backlight which results in a black screen.

With BQA1, they have the non BOE panel defined correctly with the S6D7AA0 string as I found via hex editor. That is, ss_dsi_panel_S6D7AA0_LSL080AL03_WXGA.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] lpedia:
That would explain it. How they managed to introduce such a bug is another matter.

BTW, TWRP 3.3.1-0 on T350 with LOS 17.1 thinks it's November 1973! A backup I did today is stamped 1973-11-16--19-36-43_lineage_gt58wifi-userdebug_10_QQ3A200805001 (which is why I noticed the issue). It complains (in terminal, with 'date' command) that it can't find identify the timezone code. How does it get its time? TWRP 3.1.1-1_sm-t355 had the correct time (several days ago when I took a backup of Nougat - it has a sensible timestamp). I would expect it to start from 1 January 1970, not 16 Nov 1973, if it can't get the time ...
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] lpedia:
Flashing just the stock bootloader

[MENTION=8726605]retiredtab[/MENTION], I've just tested flashing the aboot.mbn individually with Odin (3.14).

BQA1:

Create tarfile containing just the aboot.mbn file

Boot T350 to Download mode, run Odin, and flash this .tar via the "BL" section. This is very quick. Odin reports success - see attached image.

Reboot to recovery (which is TWRP 3.3.1-0). Screen comes up blank after displaying splash screen.

Reboot system via hardware keys. Screen goes blank after splash, but the system is up. adb shell works (this is what happened yesterday when I re-flashed the entire ROM, too).

BPI2:

Repeat flashing procedure with BPI2's aboot.mbn.

Boot to recovery. TWRP screen is visible.

Reboot system via TWRP. Screen stays on. Normal operation.

So there you have it ...
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] retiredtab:
Re TWRP 3.3.1, when I look at the recovery.log (boot into TWRP and then issue a "adb pull /tmp/recovery.log" from terminal), I see

I:TWFunc::Fixup_Time: Pre-fix date and time: 1971-08-10--15-39-30

I:TWFunc::Fixup_Time: Setting time offset from file /sys/class/rtc/rtc0/since_epoch

I:TWFunc::Fixup_Time: will attempt to use the ats files now.

I:TWFunc::Fixup_Time: no ats files found, leaving untouched!

On my P550 with TWRP 3.4.0.0, the recovery log shows

I:TWFunc::Fixup_Time: Pre-fix date and time: 1971-09-01--16-08-33

I:TWFunc::Fixup_Time: Setting time offset from file /sys/class/rtc/rtc0/since_epoch

I:TWFunc::Fixup_Time: will attempt to use the ats files now.

I:TWFunc::Fixup_Time: Setting time offset from file /data/time/ats_2, offset 1552452222153

I:TWFunc::Fixup_Time: Date and time corrected: 2020-11-10--20-52-15

When I do a "adb shell ls -al /data/time" on the T350, I see no such file ats_2

$ adb shell ls -al /data/time

drwx------ 2 system system 4096 Jun 13 16:11 .

drwxrwx--x 58 system system 4096 Nov 8 2020 ..

This might be related to post #18 at

https://xdaforums.com/showpost.php?p=83776003&postcount=18

I looked at the code

https://github.com/LineageOS/android_hardware_sony_timekeep/blob/lineage-18.0/timekeep.c

It might be possible that including the above repo will help with TWRP because this code

#define RTC_SYS_FILE "/sys/class/rtc/rtc0/since_epoch"
#if ANDROID_SDK_VERSION >= 26
#define RTC_ATS_FILE "/data/vendor/time/ats_2"
#else
#define RTC_ATS_FILE "/data/time/ats_2"
#endif

shows that is trying to create /data/time/ats_2.

As to why TWRP 3.1.1-1_sm-t355 has the correct time, I would have to see the recovery.log from that TWRP version wrt to the Fixup_Time function. Perhaps it's implemented in a different way than looking for /data/time/ats_2 or it's stored in a different location like /data/vendor/time/ats_2?

I'll see if I can incorporate the timekeep function in the next few days into another build. It shouldn't be too difficult, but the whole build, compile process takes several hours IF I don't make a mistake. I usually start it before going to bed and hoping it doesn't stop 5 minutes into the process (which has happened before). If I do a "make clean" to start, compiling takes about 9 hours to finish.

PS. I got burnt relying on TWRP to backup my partitions on one particular tablet. I still have not resolved how to unbrick it yet.

---------- Post added at 03:10 PM ---------- Previous post was at 03:08 PM ----------

Glad the BPI2 1MB aboot.mbn flash works. If you can upload your working TAR file, that will save people in the future of possibly asking how to make a tar file, creating it incorrectly, etc, etc.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] lpedia:
How to flash stock bootloader with Odin

To flash just a bootloader with Odin:

Extract the aboot.mbn file from the .tar.md5 ROM package, and (using something like 7-zip) create a .tar archive containing just that file.

Boot the T350 to Download mode and connect it to your PC with USB cable.

On the PC, run Odin. Click the "BP" button and navigate to the tar file you just created. Click Start.

Odin should flash the aboot.mbn and report "All threads completed (succeed: 1 / failed: 0)".

Reboot the T350.

I've attached a zip file containing T350XXU1BPI2_bootloader_only. tar and a README.txt file with explanation and instructions. T350XXU1BPI2 is the bootloader that's been shown to turn on the display panel. :)
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] retiredtab:
Those who stumble upon this thread will thank you for the tar file. :good:

I have links to pages 61 and 62 here to my lineageos and crDroid SM-T350 thread and let nubianprince and lividhen99 know about this via PM.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] lpedia:
Might be a while before I can get my hands on a T350 again to flash the older TWRP and extract a recovery log ... the two I was working on belong to other family members who had lost interest in them. After I updated my T710 to LOS 17.1 recently, they gave me the T350s to play with. Now that both devices are on LOS 17.1 and seem stable, they like the look and have taken them back! Let me know if you do need to see the 3.1.1-1_sm-t355 recovery log. I can pull rank if necessary. ;) I will pass on any feedback on issues they encounter with the build, in any case.

9 hours to build from scratch?! Fingers crossed it does stay up overnight ... :fingers-crossed:
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] retiredtab:
You don't have to. I just downloaded it myself and loaded it. With heimdall flashing, it's super quick.

Here is the recovery log. It too can't find any ats_2 files, but it defaults to 2015-08-11--08-50-45

I:TWFunc::Fixup_Time: Pre-fix date and time: 2015-08-11--08-50-45

I:TWFunc::Fixup_Time: Setting time offset from file /sys/class/rtc/rtc0/since_epoch

I:TWFunc::Fixup_Time: will attempt to use the ats files now.

I:TWFunc::Fixup_Time: no ats files found, leaving untouched!

However, when I open a terminal inside twrp and run "date". I get

Wed Aug 11 08:59:27 MDT 1971

PS. Glad to hear your family members are using the T350s again. We have so much electronic waste in this world. It's one of the reasons I run all my OS lean and mean like using Lubuntu and Lineageos with no gapps whenever possible. I try to squeeze every last ounce of performance and usability before finally passing it on to someone else for free.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] retiredtab:
Time problem fixed.

Continued at

https://xdaforums.com/showpost.php?p=83906999&postcount=39

since it's not a TWRP problem and really doesn't belong in this thread.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] tiptel170:
In my case this will not working the TWRP 3xxx in my SM-T555. It will booting with the twrp, but first has the display white lines, after 10 sec, cames the TWRP. But, it is useable. The buttons there, I will touch install cames "Adwanced" and the others buttones is the same thing, for swiping I `ll must swipe at the headline of the twrp.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] Kayser:
Hi,

Check the next posts after mine, there is the solution to get it working properly.

I managed to install it after editing a file, sadly widevine was not working on Lineageos for this device and I got back to stock.

Good luck.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] retiredtab:
@lpedia, so I had a look at twrp_3.1.1-1_sm-t355_251117.img using vi and sure enough the BOE is defined in there. See attached image.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] Zinnath Ara:
Somebody please help me!

Yesterday I tried to install custom recovery in my SM-T350. Firstly I tried TWRP 3.3.1 but it didn’t work. It was just showing black screen. I think this is because of

BOE Panel problem but then I managed to install TWRP 3.1.1 and that worked perfectly. Then I wanted to install crDroid custom rom but I found that I couldn't install this rom with TWRP 3.1.1 So, today I was looking for how to fix this problem and install TWRP 3.3.1 that will work.

I found a fix in xda where I need to just flash a file via odin and this will solve the BOE panel problem. The file is

T350XXU1BP12_bootloader_only .tar and I successfully flashed it as described in the Readme .txt file after that I pressed

(power+volume up+home) button and then the screen went black. I pressed button with different combinations, but nothing was coming and still nothing is coming. I think I hardbricked my device. So what can I do now to unbrick it? Is there any solution?

(Sorry for my bad English)

Saad.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] lpedia:
@Zinnath Ara It might be that the device is working but not turning on the screen in spite of that bootloader.

First, force it to reboot: hold Volume Down and Power for at least 10 seconds or until the boot logo comes up. Then connect it to your PC and do power+volume DOWN+home (hold for at least 5 seconds if the boot logo doesn't show) to go to Download mode. Run Odin and see if it can detect the device. If so, you can flash the stock ROM to get it working again.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] Zinnath Ara:
No, nothing is coming. The screen is still black. I tried holding the power button and volume down for 1 minute but boot logo is not coming. I can't go to the download mode also. The screen is pure black. I also connected my device with my charger but nothing is showing.

What I will do now?

Saad
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] retiredtab:
You need to hold down 3 buttons to get into download mode.

Power, volume dome and home button. If working, download mode should display in under 10 seconds.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] retiredtab:
You need to follow the instructions lpedia gave you exactly. He didn't ask you to connect your tablet to a charger, he asked you to connect to a PC running odin. If odin can't see it, then you have a bricked device.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] Zinnath Ara:
1) I tried going to the download mode but download mode is not coming. The screen is showing nothing.

2) Odin is not detecting my tablet.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] retiredtab:
You have a bricked device then.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] Zinnath Ara:
So how to unbrick it?
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] retiredtab:
The only other option is to take apart your tablet, disconnect the battery for 10 minutes, replug in and then use an usb power meter to see if the tablet is drawing power or not.

If it is drawing power, let it charge for 5 hours and try download again. If it doesn't go into download mode, then it's hard bricked.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] Zinnath Ara:
Now If it is hard bricked what will I do?
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] retiredtab:
I not an expert, but I suspect you will have to pay someone to reprogram it using jtag or have someone replace the bootloader chip or reflash it using specialized equipment.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] Zinnath Ara:
ok, thankyou.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] lpedia:
The power+volume down combination forces a non-responding Samsung device to power off. If it's on power (eg connected to charger) at the time, it's supposed to power off and stay off. If it's not on power, it turns off and then immediately comes back on and reboots.

Sometimes, powering a device right off and then leaving it off for a while will bring it back to its senses.

Hold power+volume down for 30 seconds or so while it's on the charger. You won't be able to tell whether it has powered off or not, but leave it for 10 minutes or so before trying power+volume down+home. Even if it still hasn't shown the boot logo, plug it into the PC and check whether Odin can see it. If it has silently gone into download mode, Odin will be able to see it.

I had a similar issue with my T350 once. I thought I'd bricked it, but I went through the above process (several times, if I remember correctly!) and was finally able to get Odin to see it again. In the end, the important step seemed to be to get it to power off and stay off for a while.

Good luck!
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] lpedia:
... disconnecting the battery as @retiredtab tab suggests is, of course, another way to make sure it powered off completely. :)
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] retiredtab:
Samsung Galaxy Tab A Battery Replacement

A battery, after a certain period of time, will begin to lose its life span after a charging period. This guide highlights how to remove the back...

www.ifixit.com
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] retiredtab:
@lpedia, I found this excellent article describing how the boot process works on the Snapdragon 410 and all it's partitions.

Secure boot on Snapdragon 410 - Timesys

Qualcomm Snapdragon processors support secure boot which ensures only authenticated software runs on the device. By configuring the processor for secure boot, unauthorized or modified code is prevented from being run. The authenticity of the image is verified by use digital signatures and...

www.timesys.com
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] alecxs:
anyone know for TWRP 3.4.0-0 gt510lte
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] DjLeleX:
Hey,

@/ virsys is actively maintaining the gt510wifi version, and (I think) he could build the ones for gt510lte (as the devicetree has been published by @/ ashyx). Anyway I'd love the have one updated twrp for my gt510lte, but I'm not able to build one by myself, so I think we won't have it until someone skilled actually builds it.

The latest version for the gt510lte is 3.1.0-0 (published by ashyx I think) as the 3.3.1-0 on the net isn't working.
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] alecxs:
did a stupid mistake and flashed U3 now bootloader is not unlockable anymore
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] fire_qc:
Please super help anyone!

Succeded to install TWRP 3.1 but after trying to fix the BOE blank screen I flash only ABOOT and RECOVERY partition, since then, no screen blank all the time even the download mode is blank.

Any ideas please???
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] lpedia:
Which device do you have?

Does it show the Samsung boot splash on reboot, or nothing at all?

Can Odin / Heimdall detect it if it's in download mode?

Have you tried re-flashing the entire stock ROM, not just ABOOT and RECOVERY?
[Samsung Galaxy Tab A series ROMs, Kernels, Recover] fire_qc:
Device Samsung Tab A SM-T350 2017 with Nougat out of the box.

No Samsung splash nothing at all no lights no logo when connected.

Heimdall or adb or even my Linux PC didn't detect it..

At my last attempt, flash only ABOOT (from the Marsmallow ROM) and RECOVERY 3.3.1 and after that nothing...

Tried all combination possible with buttons, but no behaviors..