Try the ROM again or try a different ROM that will partition you Nand ram differently to avoid the bad blocks that are causing the error.
You will need to flash it with NVflash recovery to restore it to functionality.
The previous flash didn’t write properly to your boot partition so you cant boot android and select reboot to recovery (which will boot CWM recovery from the recovery partition). Because you cant boot Android there is no way easy was to boot the recovery partition (where CWM recovery is located). The way to fix this is to use NVflash recovery to flash a ROM with a PC.
To put the tablet into NVflash mode the table first needs to be switch off properly. Sometimes it looks off when its not. To get around the hold the power button for 10 second before you start the back/power button thing. Now hold the back button for at least 2 seconds, without releasing the back button press the power button for 2 seconds and then release it, now keep holding the back button for a further 2 second. You will now be in NVflash mode, if you where connected to the PC while you did the back/power button thing the Pc should have pinged to say the device has been