The question is what was the car in the shop for? Why did they wipe the engine down? What were they doing? Were they doing testing where they might have caused a voltage spike to the system? Happened to me when they were testing my 4th gear solenoid-shot a full 12 volts and blew the solenoid out that was just fine before.
So what’s the full story. What kind of shop, what was the work to be done, etc? Also its a short not a shortage. A short is where a positive wire is rubbing up against a ground source causing a short circuit, which will blow a fuse.
If your asking a detail shop for advise to fix your radio i doubt you’ll get anywhere. Shorts and blown fuses are fine guesses but someone will have to diagnose the problem.
FWIW I have had a number of customers bring a vehicle in with a dead or locked up electronic module after they vacuumed the interior of the vehicle. Electrostatic discharge can sometimes find its way to sensitive electronics. Disconnecting the battery for a period of time can sometimes restore operation.
Even though you stated the fuse is okay it may not be doing any good. If a fuse doesn’t have power getting to it you get the same results as a bad fuse, no power. Power needs to be checked at the fuse to make sure that is good. If it is, you move on from there.