[Samsung Galaxy Tab A series Guides, News, & Discus] Telek:
Sorry for the delay in my updates. Got slammed at work.

So I rooted about a dozen tablets, and each time I had to do the wipe data in TWRP. Not one of them would boot after installing TWRP. However, if I followed your instructions exactly, I found that wiping data in TWRP alone wasn't enough. In a few cases the data partition was entirely destroyed, so I had to do an advanced wipe and tell it to wipe "internal storage" as well.

I think it may have had to do with which settings were selected in ODIN when I flashed TWRP. If I followed your instructions exactly (only unselecting reboot and leaving NAND ERASE selected) then I think this problem can occur.

Since I did many tablets, I was able to recreate this. When it locks up on the second SAMSUNG screen, if I ONLY do a wipe data then it will boot, but the tablet is broken. Here are my notes:

Storage is broken. Device care screen shows "7.1 GB / 8GB" storage, except there's nothing that is 8GB. The data partition is 24GB.

Trying to go into the storage details in device care would just crash

Google Play says 1.3GB of 24GB used. But trying to do any update tells me that I have to free up space.

ADB says that /dev/root is 3.5G in size and 97% in use with 148M free (this is normal).

Settings/Storage says 10.7GB used (System memory 9.4GB) with 920MB in apps, of 32GB total

On another device, Device Care/Storage says 10.83 / 32.00GB in use, not the 8GB shown on the other device.

There is no /dev/fuse -> /storage/emulated mount.

Went into recovery, did wipe, advanced, wipe just the internal storage, and rebooted - fixed the problem!

Ultimately the solution for me was to unselect EVERYTHING in ODIN when I flash TWRP. That includes unselecting NAND ERASE and F RESET TIME. This will let me skip having to do the extra advanced wipe.

With NAND ERASE selected, I noticed a note on the screen when flashing TWRP that said "ERASING USERDATA PARTITION" - so I assume that's what is causing the problem.

BTW This has nothing to do with rooting. I tried only flashing TWRP and multidisabler, and the problem still happened. I played around on a fresh device:

Did the OEM unlock, factory reset, skipped WiFi and all setup, verified OEM was unlocked, installed TWRP

There is a message on screen " SECURE CHECK FAIL : vbmeta" - this is normal.

note that there was a message on screen when installing TWRP that said ERASING USERDATA PARTITION

installed multidisabler, rebooted, and locks up on the second SAMSUNG screen (waited 30 minutes).

going back into TWRP, going to mount and data won't mount and it says "Storage: Internal Storage (0 MB)".

going into repair, the /data partition is dead, present but 0MB

tried to repair, e2fsck returns error 8

after wipe data, partition is present with Size: 22943MB

I could not wipe the internal storage partition (which is /data/media) until I rebooted TWRP, then it let me.

even after wiping it successfully (/data/media) I still can't repair it, just says "invalid partition selection" - bug in TWRP?

I was able to recreate this on another device following the same steps. This next time, however, I tried to skip the wipe data and went straight to the advanced wipe internal storage. This did not let the tablet boot. I had to first wipe data, then wipe internal storage. After that it would boot successfully.

Because I was doing more research, I also tried taking a tablet that had an old firmware (and completely untouched from factory) and just flashing the latest official Samsung firmware (using CSC and not HOME_CSC). Upon reboot after firmware flash:

35 seconds to go from the first Samsung screen to the second

1m55s to "starting android"

20 seconds after that to the welcome screen where you can start setting up

Fun fact - without enabling WiFi during the setup process, the date/time ALWAYS reset to Thursday July 21st, 2022 at 3:16am. This happens to be the date of the firmware image. So it looks like there is no internal separate RTC that maintains date/time.

What is really interesting is that taking that virgin tablet, flashing the latest official firmware (which essentially does a factory reset because I intentionally used CSC and not HOME_CSC) it takes almost 3 minutes to complete the reboot and get into android. However, doing the unlock process (which also does a factory reset) takes twice as long:

from the fresh official firmware install mentioned above, bypass as much setup as possible (no WiFi, no accounts, etc)

get tablet into usable state, enable developer mode

enable OEM unlock

reboot back into android, verify that OEM unlock option is set

shut down

hold down vol up+dn and plug in USB cable

boots up into the unlock screen, proceed to unlock

tablet reboots

The timing is significantly longer. Note that TWRP has not been installed yet, this is only unlocking the bootloader:

15 seconds after reboot, android updater logo appears and after a few seconds reboots again

Takes 5m20s to get to the starting android screen

20 seconds after that to the welcome screen where you can start setting up

Also it should be noted that you don't have to disable the AUTO REBOOT option in ODIN. With all of these learnings, I found it easier to just leave all the default options selected, and just watch the tablet closely. As soon as the flash completes and the tablet reboots, immediately press and hold POWER+VOL UP. Get to the warning screen, release all keys and press power then IMMEDIATELY press POWER+VOL UP again. After 7-8 seconds it will boot into TWRP. Install multidisabler and magisk (via SDCARD is fastest but sideload works). Wipe data, then reboot back into recovery. Advanced wipe internal storage then reboot to the OS. After 2 minutes or so it will bring you back to the welcome screen, and you're rooted! Install the Magisk APK internally and you're good to go! I was able to do this to three tablets in a row perfectly.