My car is a 2009 Cooper S with the standard non-HiFi Boost radio. I've had a different set of front speakers in it for a few years now, which were professionally installed by a reputable car audio place.

I was driving to work the other day, stopped for some coffee, and when I turned the car back on the radio was just dead; nothing on the screen at all. I had the lights on and the radio buttons were backlit, but no amount of pressing the on/off/volume button or turning the car off & on would bring it back.

So far I've tested the battery with a multimeter and checked the fuses I know to check. The battery reads 12.2 - 12.5v at rest after a 30min drive and 14v+ with the car running.

I checked the kick panel fuse pertaining to radio functionality and it was fine. There were no fuses under the hood that claimed to have part in radio functionality, but they were all intact regardless.

The only fuse I didn't check is the one that's in the back of the radio because I don't want to rip the dash apart. That just sounds like a hassle, although it might be the culprit.

Is there anything I'm potentially missing beside the inter-radio fuse? I really would love avoid taking this to the dealership, but going without radio is eventually going to drive me up a wall. Any insight will help. Thanks.

Update:
I headed to my local chain auto parts store and had them hook up a battery tester (of some sort). It ended with a status of "Unstable battery". I have no idea what values it looks at to determine that status, but I figured since it was the original battery from 2009 (actually from 2008), it was probably close to the end of its life. I replaced it with a Super Start Extreme that puts out 650CCA vs the original 480CCA. The car starts fine, but still no radio. Bleh.

Update #2:
Called the dealership and talked to a service rep. He checked with his tech and confirmed that there is a fuse in the back of the radio. I asked how much it'd be just to see if that fuse is blown. He quoted 4 hours total at $500 and change. I watched a video of the whole disassembly/assembly process, and it does not look like a fun time. This is a suckfest.