Trouble with radio/ back up screen

I've had my 2010 prius car for 6 years. No problems. I am going to be selling it (got a used 2018 prius).
I got it detailed before selling it. When I got it back, the backup/radio screen doesn't work. At first the whole unit didn't work...couldn't get the 4 cd changer door to open, no beeps,no radio no map etc. So I checked the 12 volt battery. It wasn't very good. When I put the old battery back in, the door to the cd player worked, the radio worked, and the side buttons beep. However, the screen is not working.
I put a new battery in it, thinking the old battery didn't have the power to run the screen, to no avail. Screen is still not working.
I'll be checking the fuses next. I already checked some of them, but when disconnecting the battery started to get things working, I thought that was it.
Any advice? Am I missing something simple?
When asked if the detailer cleaned the engine compartment, he said he did but "lightly".