Flash the below with ODIN (thanks to bonzai3558), extract the .md5 file from the zip, and in odin choose PDA and point to that file, keep everything else blank/default. Connect Tab with USB (after it is in download mode by power on +Volume down then volume up, so it shows the yellow android with shovel) then hit Start.
this ODIN version: http://www.megaupload.com/?d=DDN6BYB2
and this pda md5: http://www.mediafire.com/?gcenefqc3khcc0c
Now when you check for OTA once your back up, itll work fine and get past 13% and go all the way (it is normal for it to stay a long time on 76%)
Best of all tablet is ROOTED
so this odin file is surely stock (and plays nice with the OTA update)
-PS: This odin file also will save your device if it is bricked or frozen (boot into download mode) power button + volume down button, then press volume up to select
*thanks pershoot for help as well