A few easy things. IF the radio is stone cold dead plug an ear phone in.
If you get sound its almost always the speaker.
Check the battery box for corrosion & broken wires.
ON/OFF switch. There are 2 wires on the rear of it. Put another wire
between them & see if it comes on.
Beyond that you will need a schematic, multy meter & luck !
When looking for the schematic use the CHASSIS number. Its on a tag
inside the radio.
73 Zeno
LFOD !