Are you on Stock ICS? or do you have custom the bootloader?
If you're on OTA Stock ICS, when booting your tablet, try holding down the volume down button, and moving the lock orientation switch on and off, that should erase data and cache, essentially a factory reset. If that doesn't work, you might have to pull out your SD card, and get an OTA update zip.
http://xdaforums.com/showpost.php?p=25590039&postcount=131
Place the downloaded file onto the root of your SD, then reboot the Iconia and hold the volume up key. This will force it into the recovery to reinstall ICS.
If you're not on stock, boot yourself into APX mode, by turning off the tab, then with a paper clip, hold the reset button, while doing that, press the power button for two seconds, release power button, then release the reset button.This should bring you into APX mode. After that, use Blackthunders APX tool, provided you have your CPUID and SBK, to reflash the bootloader. This will reinstall the recovery and bootloader, from which you can re flash the ROM