I have Galaxy tab A 8.0' (SM-T355) with android 6.0.1
I followed the guide to this thread on XDA, sadly this recovery and root method are used for android 5.0 and mine is already 6.0. This caused a soft-brick where my tablet is stuck on SAMSUNG booting screen.
I tried the following:
1. Followed this updated thread here on this forums and I was successfully able to install twrp 3.0.2-1 but was unable to install the SuperSU zip since twrp won't mount the USB for unknown reasons.
2. Tried restoring the stock recovery by following the op post on stock firmware for SM-T350/T355/SM-P350/P355 but ended up with a same problem (soft-brick) and the recovery wont start at all!
3. Right now I following this post on XDA by restoring the original firmware, hopefully this will solve the problem.
I would appreciate if all the threads are updated with warnings to differentiate the android version to avoid similar problems with users.
Thanks in advance.
Update: I've even tried factory reset by using twrp but no change.
Update 2: Here is the result of Odin after trying to install the stock firmware:
<OSM> Enter CS for MD5..
<OSM> Check MD5.. Do not unplug the cable..
<OSM> Please wait..
<OSM> Checking MD5 finished Sucessfully..
<OSM> Leave CS..
<ID:0/008> Odin engine v(ID:3.1101)..
<ID:0/008> File analysis..
<ID:0/008> Get PIT for mapping..
<ID:0/008> Firmware update start..
<ID:0/008> NAND Write Start!!
<ID:0/008> FAIL! (Auth)
<ID:0/008> Complete(Write) operation failed.
<OSM> All threads completed. (succeed 0 / failed 1)