What should I do to dissolve hardened epoxy?

I have a defective electronic gadget I would like to repair myself. The problem is, the circuitry is in a small box filled with hardened epoxy. I am sure it is repairable. It seems the maker of this gadget wants a new one to be purchased rather than have the busted one repaired. I am afraid chipping off the hardened epoxy might destroy the gadget beyond repair. So, I think the best way is to dissolve the epoxy. But the big question is, what is the safe chemical to liquefy the hardened epoxy?