Radio not working after repairs

Recently I had an overheating problem with 98 Montana Transport. I had the fan motors replaced cause they weren't turning. That didn't solve the problem tho, it overheated again, it had been slowly loosing coolant, and I found out reading here about the rear intake manifold gasket common problem to this van. Mechanic had the heads repaired (were warped) and replaced head gasket, manifold gasket, valve cover gasket and drained replaced fluids and had plug wires and sparkplugs replaced also. When he brought it back the radio wasn't working. I know that's not a mechanical problem, but I sure would like to see if anyone knows why it's not working. I asked him and he said he's a mechanic and doesn't know about radios. He did say that it might have something to do with the anti theft system, but I don't have a clue how to reset. Since the van is older, does anyone know where could I find out about the codes for resetting? he checked the fuses too. Thanks.

Does the clock on the radio say LOC? Does it light up at all? Does the theftlock light flash?

Actually when I bought it 8 mos ago, the radio and clock did not light up, I could not tell which station was on. I could turn it off and own and just look for station by turning know, but never could see anything lit up. The red flash does work tho and still is flashing. Sorry.

In that case... The Head Unit is still working but in LOC mode...

Do you have the unlock code?

I don't have the unlock code, where can I find it? How much do they charge to get that code I wonder? Thank you for letting me know what to look for.