I would recommend emailing Digitech. They have always been very good at responding to repair questions I have. I'm sure they will do the same for you. Ask them how to do the factory reset as well.
if this doesn't work, post back here and I'd be glad to give you some help. I would like a copy of the schemo if you can send it to me. I'll look at it while you email digitech.
cjlectronics at yahoo dot com