This is the stock ROM to restore to factory settings, the tablet.
Thanks to Alex9000 for the various tests;)

Flash via fastboot
Download the archive: http://www.mediafire.com/?626q3t2zt1g8gzl
Prerequisites:
driver-adb and fastboot
copy the boot files and system-stock in C: \
start the tablet in fastboot mode
cmd to give:

Flash from recovery

Link: ARNOVA msm7627_fw8918-ota-eng_0045_0817.zip

Upload and download the rom in sd.
Here's the new procedure for the flash rom.
Download the following recovery and give the command fastboot flash recovery recovery.img.

Link: recovery.img
Then give the command fastboot continuous and once you turn the tablet give the command adb rebootrecovery, you should get a screen like this:

credits to tremendo

Now press the volume - for 27 times and should appear the following inscription: MENU BACK BUTTONENABLED.
With the minus key head to wipe and clicking with your search please both the wipe.
Now go to install zip from sdcard, then click on choose zip from sd card and select the rom.
Click yes i want to ...
It will start the flash procedure, once completed go back through back button and click on reboot and the job is done.

Screenshoot: