I managed to unbrick my device (wooooooooo!).
This is how I did it (lots of trial and error, may not apply to your device!) – quick and dirty write, don't argue about interpuctuation and layout ;):
Download the rom backup from the first post (didn't get the chance to test finnless' as I unbricked right before)
unpack the zip-file, you'll see another zip-file, unpack, too.
get unpack-bootimg.pl (
http://files.coralic.nl/unpack…..bootimg.pl)
use the .pl file to unpack the boot.img (you'll now have: boot.img-kernel.gz and boot.img-ramdisk
copy all files from the system folder into boot.img-ramdisk/system (override if necessary)
re-build the ramdisk with (attention linux-command!): cd boot.img-ramdisk && find . | cpio -o -H newc | gzip > ../newramdisk.cpio.gz && cd ..
now put tablet in fastboot mode: Power-up+Volume (keys will flash, wait until "unflash").
connect tablet to pc (note: if in endless boot-loop, disconnect from any cable first, hit reset and then put tablet into fastboot mode (pressing reset while connected to power-plug or pc will result in entering qualcomm programming mode!))
issue: fastboot boot boot.img-kernel.gz newramdisk.cpio.gz
tablet will flash the stuff and boot automatically. It will tell you something like "safe mode" in lower left corner.
NOW the important part! the screen will flicker with a selection screen known, then having more than one browser (or similar) quickly press the one of them (trial and erorr), so that the startup wizard launches, go through the wizard (may be done more than one time) tablet will when work.
If phone never exits safe mode re-flash unmodified boot.img: fastboot flash boot boot.img
and to the step with the startup wizard again (that was the point there mine started working again).
Don't blame me for this beeing stupid, but it worked for me :)