OK, meanwhile its solved. See below. Thanks a lot!
> Have you tried to factory reset with the hardware buttons after flashing an A101 rom? Sometimes it is needed if swapping between HC and ICS roms.
I did now the update.zip procedure with your suggested SD_Acer_A101_1.013.09_COM_GEN1_full_user.zip
After that it was the same: only the Android letters scroll screen.
Because the stock recovery menu does not work to select something and even more I did not get how to reset the device by hardkeys I used the RESET hole and sticked something in for some seconds, then it rebooted but its still the same:
I get only the Android letters scroll screen.
Could this depend on the combination of A100 and A101 ROM needed?
Could this depend whether you do OR DO NOT the commands between like in this "how to root instruction"?
I am out of ideas. All I can currently do is going back to an A100 ROM, so I lose 3G
OK FOLKS. ALL SOLVED. AFTER I FOLLOWED THESE INSTRUCTIONS _AFTER_ FLASHING A101 ROM:
The only curious thing is that I am now fixed to Android 3.2.1, when I click System-Update it says device would be on latest version, but maybe this takes some time.