Probably a new clock
Tach module?
Forget the radio if it was OE, they are crappy anyhow.
Your homeowners insurance may cover this kind of boo boo. I heard of a case where an owner changed oil, did something wrong like putting two O-rings on the oil filter cover, and when the engine locked up a few miles down the road it was time for an engine rebuild, and his Homeowners paid for it. Must have a pretty comprehensive policy, huh?

I heard of a AAA tow truck driver that hooked the jumper cables backwards and he said something like oh Sheeet! when sparks flew. The cars owner was right there and witnessed it. He had to to threaten to sue them after trying to collect to get the car fixed. The bill was over $2000 for new electronic modules, etc. but then AAA balked at replacing the clock.
I was amongst a bunch of MB owners that signed a declaration that basically said MB clocks last a long time. AAA was basing the lack of insurance coverage on the clock on the belief they held that "most clocks are shot after 15 years" - this was only a 15 y.o. 560SEL. AAA finally caved in, I couldn't believe they refused to take responsibility for everything.

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body. '87 300D w/ Sportline suspension. No more '79 300TD w/ 617.952 engine at 367,750, it was my annual driver to Texas and I sure don't miss it poor A/C heater system!