yashsingh1/xdaforums huggingface dataset:
[Zenfone 2 Laser Q&A, Help & Troubleshooting] BubuXP:
I'm investigating what happens in detail when these two partitions are erased.

I found two discussions that look interesting (specially the second):

http://xdaforums.com/zenfone2/general/investigation-efs-t3153154

http://xdaforums.com/showthread.php?t=2617276

In brief: these two partitions holds important information of the phone, like the IMEI. Erasing them cause the system to recreate them using the information backed-up in other partitions. But in some cases these backup partitions are empty and erasing the modemst partitions cause the phone radio to stop working (no more calls, 2G/3G/4G data and GPS) because the system cannot retrieve the serial numbers needed to make the radio work anywhere.

So it's better to do a manual backup of these partitions before erasing them (better a full backup with TWRP, that will backup all partitions including these).

Reading the second discussion linked above suggests me that the sudden bootloop problems that people are experiencing, are also connected to the corruption of these modemst partitions (corruption possibly caused by some firmware update or by some system app gone mad).

The fact that Asus after 2+ months still hasn't fixed the GPS problem, could mean IMO:

- that the problem isn't related to the above partitions and is more complicated than it seems (probable);

- that the problem is caused by the corruption of the partitions but it cannot be fixed with an OTA firmware update, but only manually with a technical intervention (full flash and/or terminal bashing) that regular users aren't capable of;

- that the problem can be fixed with a firmware update but Asus developers still haven't find that (improbable).

I should get the ZE500KL in a couple of days, then my theory could be tested directly and described in detail (if I get the same GPS problems after updates).
[Zenfone 2 Laser Q&A, Help & Troubleshooting] rozene05:
Thanks for your input regarding this, i would just use my bluetooth gps in order to navigate properly..
[Zenfone 2 Laser Q&A, Help & Troubleshooting] BubuXP:
Yesterday I received the phone, I booted it to check if it works, then I immediately upgraded the firmware to the latest version, without OTA updates but downloading directly the latest full firmware from the Asus download site.

Then I booted the phone, played a little with it, did a full reset and re-flash the firmware.

Then I thought about GPS problems and I tested it with AndoiTS GPS Test and it seems to work fine, or at least I suppose this from the attached screenshot (I couldn't test it on the streets yet).

I don't have root permission or bootloader unlocked [yet], so you and everybody could try the same things I did:

- Factory data reset (from Settings > Backup and reset menu);

- wipe data/factory reset (boot into recovery by pressing Volume Down button while turning on the phone);

- full firmware flash (from recovery, you can copy the firmware zip file in a microSD or upload it via adb sideload).

Then after rebooting the phone complete the welcome procedure and repeat the three steps above another time.

I hope this will works for everybody.
[Zenfone 2 Laser Q&A, Help & Troubleshooting] rozene05:
Here is my screen shot using asus zenfone 2
[Zenfone 2 Laser Q&A, Help & Troubleshooting] rozene05:
Screenshot from asus zenfone 2 ze500klView attachment 3688164

Merely 2 satellites :(

And here is the screenshot using xperia sp c5303,

View attachment 3688165

I also updated using the zip in asus site and flashed it,

Btw, my asus has been rooted, but i see no difference after rooting it, same scenario 2 or less satellites, some times 5 but no fix
[Zenfone 2 Laser Q&A, Help & Troubleshooting] rozene05:
Another question what firmware version are you using, as far as my experience, the latest ww.12.8.5.222 firmware gives me this problem so i decided to do a full downgrade to the stock fw that comes with my phone, which is ww.12.8.5.118, for that fw works before
[Zenfone 2 Laser Q&A, Help & Troubleshooting] BubuXP:
I used the latest firmware, the .222

The trick could be resetting and flashing, two times, but it's only an assumption.

BTW, into geolocation settings, I enabled the only GPS option when doing the test.

In your screenshot, it looks like AGPS is enabled, that is not GPS. Try setting only GPS in the geolocation settings and see what happens (maybe with screenshot).
[Zenfone 2 Laser Q&A, Help & Troubleshooting] rozene05:
Here it is without agps, i even left my phone in the open for about an hour, screen on, hoping it will fix even with one satellite, now even one satellite wont show upView attachment 3688327
[Zenfone 2 Laser Q&A, Help & Troubleshooting] BubuXP:
Ok, it looks like the same exact problem as the Moto G, and the solution should be the same too.

But with the bootloader locked (and no way to unlock it at the moment), the only thing we can do is using the terminal with root privileges to backup and erase the partitions (with the dd command or something similar).

I'll study how to do this...
[Zenfone 2 Laser Q&A, Help & Troubleshooting] rozene05:
Just to update

View attachment 3689322
[Zenfone 2 Laser Q&A, Help & Troubleshooting] 4llerbuntu:
so what did you do to solve it?
[Zenfone 2 Laser Q&A, Help & Troubleshooting] BubuXP:
Even if you don't have GPS problems, could you please run these commands in the phone's Terminal app (you can download it in Play Store) or via ADB shell?

cat /system/build.prop | grep "^ro.product." | grep -v "^ro.product.locale." > /storage/emulated/0/xinfo.txt
cat /proc/partitions >> /storage/emulated/0/xinfo.txt
ls -l /dev/block/platform/*/by-name >> /storage/emulated/0/xinfo.txt

You will get the file xinfo.txt in your phone's memory. If you post here the file (or the file's content), I can check that the partitions layout is the same for every ZE500KL, just to be sure before posting a possible solution for the GPS problem (it will require root permissions and busybox installed).

Thank you.
[Zenfone 2 Laser Q&A, Help & Troubleshooting] BubuXP:
179 64 31166976 mmcblk1
179 65 31162880 mmcblk1p1

1970-01-02 07:29

It's identical to mine, except for these lines.

The first two lines are probably referred to the external memory. I have a 16GB microSD and my value is half yours, so you should have a 32GB microSD in the phone, right?

My date of creation of the listed elements instead is 1970-06-23 07:13 and I don't know why. I could suppose it's because of different firmware version, I am on WW_12.8.5.222

I'm testing, I will be back hopefully with a working solution.
[Zenfone 2 Laser Q&A, Help & Troubleshooting] rozene05:
i do have a 32 gb card
[Zenfone 2 Laser Q&A, Help & Troubleshooting] BubuXP:
Our target is to erase the modemst1 and modemst2 partitions, but we have to backup them before, just to be sure that we can revert back if something goes wrong.

If you don't know what you're doing stop right here, as you could lose the ability to make and receive calls (and lose 2G/3G/4G data connections too).

If you get errors while doing the following, don't ignore them and report them here before proceeding, if you don't understand the error message.

I tested the following method, it must be executed from phone's Terminal app or from ADB shell.

Prerequisites: rooting and Busybox.

1) First go to your Settings, select "Location" and flip the switch to the "Off" position. Then elevate to root and check where your modemst partitions are located:

su
ls -l /dev/block/platform/*/by-name | grep modemst

if you have the same model as mine (ZE500KL) this should be the output:

lrwxrwxrwx root root 1970-06-28 06:30 modemst1 -> /dev/block/mmcblk0p16
lrwxrwxrwx root root 1970-06-28 06:30 modemst2 -> /dev/block/mmcblk0p17

where /dev/block/mmcblk0p16 and /dev/block/mmcblk0p17 are our target partitions. If your results are different, please change the following commands to reflect the differences.

2) To backup:

mkdir /storage/emulated/0/modemst
busybox dd if=/dev/block/mmcblk0p16 of=/storage/emulated/0/modemst/modemst1.bin conv=notrunc
busybox dd if=/dev/block/mmcblk0p17 of=/storage/emulated/0/modemst/modemst2.bin conv=notrunc

you can copy the two backup files to the microSD and/or your PC, just to be sure. You can do a full nandroid backup to be even more surer, but it must include ALL partitions, like the modem ones.

3) To erase partitions and reboot right after:

busybox dd if=/dev/zero of=/dev/block/mmcblk0p16 conv=fsync
busybox dd if=/dev/zero of=/dev/block/mmcblk0p17 conv=fsync

Then long press the power button until the menu appear and select the reboot/restart option. After restarting you must check if Bluetooth, WiFi, phone calls and 2G/3G/4G data works. To test GPS go to Settings > Location > enable only GPS and then download and use AndroiTS GPS Test to see how much satellites you can get in the list.

4) Do this only if something doesn't work after the restart. We can go back to the former situation by restoring the original partitions:

su
busybox dd if=/storage/emulated/0/modemst/modemst1.bin of=/dev/block/mmcblk0p16 conv=fsync
busybox dd if=/storage/emulated/0/modemst/modemst2.bin of=/dev/block/mmcblk0p17 conv=fsync
[Zenfone 2 Laser Q&A, Help & Troubleshooting] rozene05:
what must be the output after i run this?

busybox dd if=/dev/zero of=/dev/block/mmcblk0p16 conv=fsync
busybox dd if=/dev/zero of=/dev/block/mmcblk0p17 conv=fsync

this is my result

Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation. All rights reserved.

C:\Users\Zene>adb shell
shell@ASUS_Z00E_1:/ $ su
su
root@ASUS_Z00E_1:/ # busybox dd if=/dev/zero of=/dev/block/mmcblk0p16 conv=fsync

box dd if=/dev/zero of=/dev/block/mmcblk0p16 conv=fsync <
dd: writing '/dev/block/mmcblk0p16': No space left on device
3073+0 records in
3072+0 records out
1572864 bytes (1.5MB) copied, 3.209385 seconds, 478.6KB/s
1|root@ASUS_Z00E_1:/ # busybox dd if=/dev/zero of=/dev/block/mmcblk0p17 conv=fsy
nc
sybox dd if=/dev/zero of=/dev/block/mmcblk0p17 conv=fsync <
dd: writing '/dev/block/mmcblk0p17': No space left on device
3073+0 records in
3072+0 records out
1572864 bytes (1.5MB) copied, 3.402028 seconds, 451.5KB/s
[Zenfone 2 Laser Q&A, Help & Troubleshooting] rozene05:
still have a hard time locking

View attachment 3695434
[Zenfone 2 Laser Q&A, Help & Troubleshooting] BubuXP:
At least the GPS is now switched on, something has happened.

What version of the firmware are you using right now?

Maybe doing the erasing commands in recovery mode (via ADB in TWRP) could change something.

Or "simply" reflashing the full firmware after a device reset...

I tested on my device that the procedure causes no problems, but because the GPS was already working fine on my phone, I couldn't know if it was the final solution.
[Zenfone 2 Laser Q&A, Help & Troubleshooting] rozene05:
actually it worked for a while

View attachment 3695684

but after..

View attachment 3695687

i dont know what just happened
[Zenfone 2 Laser Q&A, Help & Troubleshooting] rozene05:
can i see the results of your terminal outputs?
[Zenfone 2 Laser Q&A, Help & Troubleshooting] BubuXP:
I'm not at home at the moment. And by the way I use Debian, not Windows but this should not change anything in practice, I suppose.

My terminal output looks almost identical to your if I remember well, but later I will post them.
[Zenfone 2 Laser Q&A, Help & Troubleshooting] rozene05:
for now it is working!

thank you so much!

View attachment 3695824

View attachment 3695825

i will keep you posted if it will fail for i will be having a long drive later
[Zenfone 2 Laser Q&A, Help & Troubleshooting] sofamensch:
Thats good news so far. For me the problem manifests this way: Although getting GPS fix, it looses signal once every minute or so, and then starting catching gps all over again with error>50m, making navigation impossible.

How are your results?
[Zenfone 2 Laser Q&A, Help & Troubleshooting] Math43:
Hi,

Same problem for me...
[Zenfone 2 Laser Q&A, Help & Troubleshooting] BubuXP:
If the fix doesn't work, you can retry leaving the GPS only option enabled during the entire process, and if this doesn't work try doing a phone reset before retrying, if that doesn't bother you.

If even after the reset the fix doesn't work, try [re]flashing the latest full firmware, as I explained here:

http://www.asus.com/zentalk/forum.php?mod=redirect&goto=findpost&ptid=70573&pid=341189

and then retry with my fix.

Other oddities that could make a difference even if it seems improbable: instead of giving the command reboot in the procedure, try restarting manually (or power off) the phone with the physical button.

Also, after booting in fastboot mode, try giving the commands:

fastboot erase modemst1
fastboot erase modemst2

even if it says it's not doable. Then retry the process.

I don't know other possible solutions at the moment.

BTW, I found that in some cases (like for example after a firmware update), the phone's GPS needs about 15 minutes in good open place to get the satellites' map and become full working.
[Zenfone 2 Laser Q&A, Help & Troubleshooting] sofamensch:
After finding a way to root without unlocking the bootloader I have tried this fix.

First time following it failed, luckily I could restore it using the Backup I made before using your commands. The IMEIs of the sim cards wouldnt show up. I retried, this time with GPS On and Manual Reboot. It worked out OK this time for the SIM Cards. So be sure to back up! GPS reception is currently worse / non existing.
[Zenfone 2 Laser Q&A, Help & Troubleshooting] sofamensch:
Good news everyone. I tried some further, this is the combination which finally seems to have worked:

-root (there is an instruction which works without unlocking the bootloader - no loosing guarantee!)

-first a clear cache and user data

-following the instructions as in previous posts, restarting -manually- and not by cmd line.

-During the next boot I saw a message "Android is upgrading".

Since that time I have continuos good reception, many sats and no interruption on 222 firmware.

My precise setup is:

ASUS ZenFone 2 Laser(Z00E/Z00ED/Z00EDA/Z00EDB)software Image: V12.8.5.222 for WW SKU only*
[Zenfone 2 Laser Q&A, Help & Troubleshooting] rozene05:
so long after i drove...

as a report..

gps signal drops even on an open freeway... the previous problem reocurr.. no screenshot though..sorry

i takes a minute or two to have a fix with 40 meters of accuracy. which is kind of a bummer, as my old nokia get a fix on all visible gps, no glonass, only usa satellites..

but still a good starting point on having a good solution to the gps problem of our asus phone...

s

---------- Post added at 11:41 AM ---------- Previous post was at 11:36 AM ----------

i also noticed this while driving, accuracy isnt good, moe that 30m, you need to be stationary for about a minute to have a decent accuracy , but the moment i move/drive gps go crazy and restart finding satellites...

---------- Post added at 11:43 AM ---------- Previous post was at 11:41 AM ----------

i may try it, i am on an older fw .172 . for you know themes are broken in the latest fw [emoji1]
[Zenfone 2 Laser Q&A, Help & Troubleshooting] rozene05:
i upgraded to .222 fw just now, i am checking for the gps.... i will report on the progress

so far, cant see gps satellirte
[Zenfone 2 Laser Q&A, Help & Troubleshooting] sofamensch:
I can confirm this error. Even after patching and while moving the accuracy is just terrible. I noticed this only after inserting a SIM card into SIM1. So try this after the erase patch, I currently get good accuracy <10m also when moving for now.

-Set Location settings to GPS only.
[Zenfone 2 Laser Q&A, Help & Troubleshooting] cLeAv0:
Can someone link me a backup of modemst1 and modemst2? I screwed up and I now have no signal. I tried copying modemst1/2 before but it shows dev/block/mmcblk0p16/17 no such file or directory. So i have no backup. Already tried to flash modem on fastboot and reflash firmware in recovery, still no signal. :(

*edit*

Lost my phone's IMEI. Anybody know how to recover it?
[Zenfone 2 Laser Q&A, Help & Troubleshooting] sofamensch:
Sorry, but we ce cannot sent the modemst1&2 partitions as the informations are device specific and sensitive.

At which step did the error occur? You should be able to find them on your internal sd card from within Android.

If all seems lost, try formatting the partitions again using dd, then manual reboot (not in command line).
[Zenfone 2 Laser Q&A, Help & Troubleshooting] cLeAv0:
I have no backup of it because dd'ing /dev/block/mmcblk0p16-17 to the internal storage keeps giving me errors. How do I format it using dd? I don't know what filesystem to use and what size to partition it.
[Zenfone 2 Laser Q&A, Help & Troubleshooting] BubuXP:
To format just follow the 3rd part of the procedure.
[Zenfone 2 Laser Q&A, Help & Troubleshooting] cLeAv0:
Already tried numerous times. Still IMEI 0/null. Weird thing is the first time I tried this nothing happened. Then I tried it again then this happens. Gonna look for ways to fix. And also bluetooth/wifi works.
[Zenfone 2 Laser Q&A, Help & Troubleshooting] sofamensch:
But its weird that you have no backup. Check the content of "/storage/emulated/", there may be a folder "0" or "legacy". I had to replace "0" with "legacy" and it works for me.

You can just check the content of the folders in adb with "ls" command.
[Zenfone 2 Laser Q&A, Help & Troubleshooting] sofamensch:
So current situation: Despite the modem1 and modem2 block resets, I still have errors. Especially when driving the error drifts far off and the old position is simply stuck, or GPS gets lost frequently.

For now, I had most problems with newer version such as 222, 172 and 156. Right now I tested 106 on a drive and it seems to behave better. So I recommend everybody for testing to first downgrade and test different versions for finding a solution.

This does not require rooting or any resets. You can find the official download links on the webpage of ASUS and flash through recovery. Device Reset is not needed when switching between versions.
[Zenfone 2 Laser Q&A, Help & Troubleshooting] sofamensch:
I did some further testing with 106 and behaves much better, even in difficult situations (such as rain), as far as I could tell during a short ride.

I have checked out a list of gps modems on the different firmwares so far. I am providing you original extracts of my modem partitions at the bottom of this post.

The GPS modem firmware seems to be located at /modem, which maps to /dev/block/mmcblk0p38 on my phone. You can just flash old 106 firmware. I am currently testing using 222 and only reflashing the 106 modem which seems to be OK. The 106 and 118 version have a different fastboot screen (it does not show fastboot header, however it works just as well) so do not be confused.

Risk is low, as /modem partition is reflashed during every firmware update. However check that you hit the correct partition block. My phone is ZE500KL / Z00ED.

So very similar to previous procedure. First check where your modem partition is:

adb shell
su
ls -l /dev/block/platform/*/by-name | grep modem

Which results for me:

And flashing a new modem:

busybox dd if=/storage/emulated/0/modem.bin of=/dev/block/mmcblk0p38 conv=fsync
[Zenfone 2 Laser Q&A, Help & Troubleshooting] cLeAv0:
It seems the file is bigger than the partition. I used "ls -l /dev/block/platform/*/by-name | grep modem" and it also says my modem partition is mmcblk0p38. But when i dd to it it takes forever to finish that I would have to ctr + c. Any thoughts?

*edit*

removing conv=fsync makes it finish instantly.
[Zenfone 2 Laser Q&A, Help & Troubleshooting] dave182:
Hi, I didn't understood one point. While to refresh the whole firmware (also the old ones) you don't need to root the phone, to flash only modem is the same, or you need to root it because you need to delete the partitions impacted?

Thanks in advance.
[Zenfone 2 Laser Q&A, Help & Troubleshooting] sofamensch:
I have been off topic for a while. Why? Because I was still not happy with the GPS performance, even after all procedures taken!

I did RMA my phone. It was diagnosed with "GPS function fail". Since then I haven't excessively tested, but it seems way better than before.

[MENTION=422028]dave182[/MENTION]

Yes you need root to access these partitions (reflash modem etc). For flashing firmware you dont.

[MENTION=3940257]cLeAv0[/MENTION]

Yes it took quite long, about a minute I remember. But just patience was also OK for me.
[Zenfone 2 Laser Q&A, Help & Troubleshooting] rozene05:
how?
[Zenfone 2 Laser Q&A, Help & Troubleshooting] sofamensch:
I tested on 1000 km drive and now the phone is my favorite again. GPS works like a charm, I am on latest 222 firmware without any modifications.

You can start the RMA process on the ASUS website.
[Zenfone 2 Laser Q&A, Help & Troubleshooting] rozene05:
How long does it take for the Rma

---------- Post added at 01:16 PM ---------- Previous post was at 12:57 PM ----------

cant seem to find it on the asus website... care to share the exact link?

What is the status of your ze500kl before RMA?

Rooted? Unlocked bootloader?

also, care to share the complete RMA process?
[Zenfone 2 Laser Q&A, Help & Troubleshooting] velikashkin:
To repair you need to disassemble the smartphone GPS and bend contacts.
[Zenfone 2 Laser Q&A, Help & Troubleshooting] ant0nk:
How to find the contacts? Cant't find appropriate disassembly video.
[Zenfone 2 Laser Q&A, Help & Troubleshooting] Stephen:
Moderator warning,

Thread cleaned. Flaming users is not acceptable.
[Zenfone 2 Laser Q&A, Help & Troubleshooting] velikashkin:
(с) autor

Three groups of green color.

View attachment 3776166
[Zenfone 2 Laser Q&A, Help & Troubleshooting] sbaragnaus_:
Hi, does new Zenfone 2 Laser ZE500KL-6J307WW solve gps issue?

Tnx
[Zenfone 2 Laser Q&A, Help & Troubleshooting] fsinatra:
I've tried the modem partition tricks as described in this topic without success.

Finally, I sent my phone to Asus support and they changed the motherboard.

Since then, the GPS has been working
[Zenfone 2 Laser Q&A, Help & Troubleshooting] crugg:
GPS firmware download problem

The 3 link don't work. I have more problem with gps fix ! :(
[Zenfone 2 Laser Q&A, Help & Troubleshooting] fxjohn:
Hello,

Owner of a Z00ED (ZE500kl), I've just updated to marshmallow (13.10 /not 13.7) and when I'm trying to root my phone (I've succeeded in install it (verified via other software) but it does not really work because system softwares I uninstall, reappear after a reboot), I've seen this topic so I've tested my GPS (which I normally don't really use). And it also do not work ; without a really good answer here, on this topic, I've searched across internet. I've found various power saving parameters ideas or multiple (times) system install, without any success.

Some people crazy talk about some paper at the back of the phone to make pressure on the motherboard. Of course, I've not tried it before I was desperate of any solution but as soon as I've tried, the GPS (only, not high precision mode) began to fix satellites again at my open window. But, I've installed Pokemon Go to test this functionality and it seems really buggy ; more of that, the new backplate form modify sounds propagation in a bad way. So it seems to be a real hardware problem.

I've thought to send back to support in guarantee but since I've unlocked bootloader I assume that I've lost this opportunity...
[Zenfone 2 Laser Q&A, Help & Troubleshooting] fxjohn:
I haven't seen this topic, thanks. But do you know if sound problems are important because I use my phone to actually call people ;) ?

Thanks in advance.

Edit:

Sorry, I've just seen your last message on the other topic so I've my answer...