Recovering mid9040

[joshuas_79]

Hi, my friend has a Coby mid9740 tablet, and he got locked with unlock pattern, so, the only thing I could was try to wipe from stock recovey, but, after that I got bootloop in android logo. I tried to go to stock recovey again, trying wipe cache, and also flashing update from cache, with no success. I also tried to flash update from sd and used that dump, but I got signature error, I guess due to stock recovery.

Any help? , tablet is not rooted, has stock recovey and adb is no activated