I have a schematic. It makes sense that it would be a circuit breaker trip, as there are no other symptoms and no output anywhere.
My real question is, is this a “service” item or a simple manual reset of the existing unit? Will I need to replace it? If so I might as well order one now. I don’t like opening a casing and finding that I need parts I don’t have, I’d rather get all ready then open the case.