(2015 Mini Cooper S)
Okay, I've been researching to no avail but I have some compounding issues probably. I installed the Bimmertech MMI Prime carplay module. Right before I did this, I used bimmercode to code LED side-indicators and remove the legal warning on the radio at start up. Worked fine, no problems, and then after this I installed the MMI module. (only mentioning this in case its relevant)

Install went fine, but on first try initially the radio would not boot past the MINI logo screen. Kept rebooting itself. I disconnected the car battery for 5 mins, and tried again. Bam- everything works! Tested everything out, and it all worked fine, so everything must be hooked up correctly. Now... I go to try again this morning, and we're back to the MINI boot screen only, and it just keeps rebooting itself! Once again, I disconnected the battery (for 15mins) but this time did not fix the issue.

Near as I can tell, could this be a symptom of a failing battery? It is old (at least 5 years afaik) but there are no other symptoms. Car ran great before this install. Anything else I can try? Is the car somehow losing it's "registration" with the head unit? low voltage? I'm stumped...

 

Okay I have now reverted everything back to stock, and the head unit is still stuck on an infinite reboot loop. How can I tell if I fried it? I have to confess--I was lazy the first time and didn't disconnect the neg batt terminal when I was installing. However, everything worked fine (for a short while) after I had installed the first time.

Now bimmercode still won't recognize it as a modifiable module even though it has been returned to stock.

I checked all fuses, all good. I did notice that the NBT module and the MMI were very hot when I opened the dash again... but even after allowing them to cool, still not working.

Hopefully some experts can chime in here! TIA

 

Thinking out loud...

If I replaced the head unit, could I theoretically use my bimmercode backup and apply it to the new NBT module after it's installed in the car? And then avoid having to get the radio coded to my VIN. Not sure if that's how it works...

 

I would at least call BimmerTech and talk to them. I have the BimmerTech MMI for a rear view camera. They were extremely helpful to me with an issue.