first thing to do is very basic. Do a physical check, look for damaged parts or burnt smell. If you have a multimeter check for continuity on wiring including transformer and switches. Make sure voltage switch is set to correct voltage, 12v or 24v. BUT BE VERY CAREFUL when powering up as that big round capacitor on top can rapidly disassemble
The list here is from the 1st echelon. Keep us informed of progress.