You could try that yeah, start at the AC input and try to find where the circuit fails. If you want to do that though I’d recommend that you take 2 good pictures of the front and the back, put them side to side and sketch out the circuit diagram. It’s no use trying to measure voltage nodes if you don’t know what they are supposed to be. Question is if that is worth your time, there is certainly some educational value but there is always a chance that you just won’t find the fault.

If you do make a schematic then react to my post. I’ll try to help you with reading the circuit if you want.