Clock/radio work intermittently

Went to a new place to get body work done. Took car home. Did not turn on radio or notice anything wrong. Next day, my radio wouldn't go on and the display showed what looked like graphic equalizer bars and none of the buttons were responsive except power. No sound. I called the place and left an upset message but it was the weekend and no response. I went to see a client for a couple of hours, got back to my car, started it, and the radio and clock were fine except the clock had lost some time. Next morning got in my car, started it and no clock/no radio. Different display. Fewer lights. Nothing that looked normal. Went to auto body place and when I got there turned off the car to go inside. Mistake! Turned the car back on and radio and clock were fine. Turned off and on again. Still fine. Guy at body shop said they had to unhook battery to work on car and it was probably a fuse. He said to bring it in next time it happened. Radio was good for a few days after that. It happened again as I was leaving town for awhile. Tried replacing fuse while I was gone. Didn't make a difference. Thought maybe cold weather affected it. But it's been really cold lately and it came back on for a couple of days so I don't think temperature is the problem. Nor does it change when going over bumps or rough road. It has been going off and on frequently. Change always happens when I start the car. Sometimes it stays off for more than a week. Sometimes stays on a few days. A couple of times it didn't work when I went to the store, but worked again when I left the parking lot. When it works, it works fine. The clock is on, the sound is good, the station presets are there. But then I park the car and I come back to it and it will then just have either nothing on display or orangish fuzzy light and silence or white noise. I could try bringing it back to the auto body place. They do mechanical work too, but I'd like to try to fix it myself if I can. Any thoughts? I don't think it's a reset code problem or it wouldn't work at all. Thanks for your help!