You could try using the Motorola tool to bring the phone back to stock ROM. Just be aware if you do it demands an email address and all contacts and (I think) to read all emails in the email account (not kidding) to use the tool. So I recommend you use an email account with no little or no data in the account.
I have another thread on it in here somewhere… actually here: Can't boot phone ID: bad key - #3 by rhubarbpieguy