A cheap AM radio can be a useful solid-state troubleshooting tool. Tune to a
quiet spot on the dial and bring the antenna (that ferrite bar with a coil
wrapped on it inside the radio) close to any digital I.C., try rebooting,
resetting and closing different switches in the system and note the changing
tones. Compare a working and malfunctioning circuit. With practice you can
identify a correct sequence of tones for each board.