I would pull the cover and check for a fuse holder or thermal breaker. The most likely cause of failure is the rectifier bridge (diodes) go bad. If you know enough to know what diodes are you probably know enough to fix it. If not, depends on if you have a good electrical "handyman" around that will not charge an arm and a leg and can "subsititute" parts needed with non-oem parts. Really not a lot of parts to a battery charger but I'm sure Shcumacker makes the oem ones expensive enough it will not be worth repairing if you have to go to them for the parts.

John