[Samsung Galaxy Tab A series ROMs, Kernels, Recover] jazzespresso:
This part of post dedicated to help and support

How to Flash Offical Firmware and then flashTWRP

Please remember that there are tons of other threads about this, do

NOT

expect that these below information bulletproof, works for all condition.

I am just providing this post as additional guide.

Advice: I usually create a temp folder on my PC and put all the files there to make it easier to work on

TWRP Download:

It is import to check [MENTION=4899305]ashyx[/MENTION] main thread for additional info or update...

T-350 - twrp_3.1.0-1_sm-t350_18317.tar by [MENTION=4899305]ashyx[/MENTION]

T-550 - twrp_3.1.0-1_sm-t550_13317.tar by [MENTION=4899305]ashyx[/MENTION]

Firmware Download:

First download Odin here Odin3-v3.12.7.zip

Download official 7.1.1 Firmware of SM-T350 or if your device is SM-T550:

https://samsung-firmware.org/download/GALAXY__Tab__A__/u646/XAR/T350XXU1CQJ1/T350XAR1CQJ1/ - T350XAR1CQJ1

https://samsung-firmware.org/download/GALAXY__Tab__A__/559n/XAR/T550XXU1CQJ6/T550XAR1CQJ6/ - T550XAR1CQJ6

Once you download it, unzip it, you should end up tar file, such as example; T350XXU1CQJ1_T350XAR1CQJ1_HOME.tar

Steps:

Now that you have all the files on your PC/Mac, let's start:

Be master of switching back and fourth of holding keys Home, Down Vol, and Power all at the same time - practice this!!

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Firmware:

1. First, do a rest your tablet - so all the junks will be cleaned up and your tablet will be first time setup use.

2. Now, put your tablet in download mode (make sure it is not connected to your PC with USB); To enter Download mode, press and hold Home, Down Vol, and Power all at the same time, until you see the Warning screen of the download mode. Press Vol up to continue, you should be in download mode now

3. Connect your tablet to your PC and then open Odin3-v3.12.7, confirm that ODIN can see your tablet (ID:COM should say Added!!), click AP button on Odin. In popup, select tar file you downloaded firmware, click OK...it may take several mins to load firmware since it is big, also MD5 check..etc...once done, click Start

4. The screen of the tablet should show a progress bar as your tablet is being restored to its original firmware.

5. After flashing, the tablet should reboot into Android.

6. Reboot may take some time, but after a while, you will be greeted with the Welcome screen where you can select your language, etc....do not setup google account nor Samsung account, just skip, skip...until you see home screen.. Now, plug in your tablet to your PC, and then copy JazzROM zip to your tablet (remember where you place it on your tablet), and then go Settings, About tablet, and click 7 times on build number to enable Developer Option, go there and check USB debugging option active..

Up to this point, you should be now on official 7.1.1 firmware...

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TWRP:

7. Now Power off the tablet using the power button...

8. Put your tablet in download mode again (step 2 above)

9. Open Odin again, and select AP button on Odin. In popup, select your device's twrp-XXXX.XXXX.tar, click OK, and then in Odin go do Option (next to Log tab) and uncheck Auto Reboot!! - this is critical!!

10. Now, click Start, it should flash it OK and should say success.

11. It is important, we did select uncheck Auto Reboot, means your tablet still in download mode.

12. Still download mode, unplug your tablet from PC, and quickly Hold [Volume Down] + [Home] + [Power] to get out of Download mode, and screen goes black blank a sec, immediately swap to [Volume Up] (while still holding [Home] + [Power]) -- if you can't reboot into TWRP, you need to re-flash it again until successfully reboot into TWRP.

13. In a few secs, you will see bit waranty......: recovery top on left screen, and then you can let go of all the buttons.

14. You should now see TWRP, Swipe to Allow Modifications.

15. Now, let's do Backup, select that and select Storage, and select MicroSD card (or internal if you don't have microSD card), from backup, select partion to backup, select all of them, and do swipe to backup.

16. Now, you did full nandroid backup (in case you want to restore), click back button until you are on main screen, and click Wipe option, and do Format Data, type yes on the screen..it will format your data. Now, click Advance Wipe, and select only Dalvik /Art Cache, System, Data and Cache, and swipe to wipe...it may take a few sec, once it finish, click back, back..until you are main screen

17. On main screen, click Install, locate JazzROM zip file (where you put in step 6 above), and flash it...when it finishes, select wipe Dalvik /Art Cache, let it finish that too, and then select Reboot.

18. TWRP will prompt if it will install TWRP as system app, say do not install.

19. Your tablet should start rebooting...

20. Reboot may take anywhere 10 mins to 20 mins, be patient here...once it reboots, it should says initializing android black screen..let it finish all up until you see welcome screen...wait for a few mins on welcome screen, and then continue your setup as you normally do.

21. If all goose fine, you should be running JazzROM Nougat 7.1.1

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I may update this post based on feedback from you guys....