I merely reinstalled the firmware - some (many? most?) firmware updates for the EB600 actually install the complete software, which is why it might work if you merely ruined the current system.
This post:
https://www.mobileread.com/forums/sho...7&postcount=15 has a link to instructions and firmware.
Of course, it'll be Cool-Er firmware then. You might try to find the original firmware - if it exists in an installable form. But if you can get the Cool-Er firmware running, you can always change again later on.
Obligatory warning: this might work - or it might not. Consider the risk and decide for yourself if you want to try.