My Mac Mini Late 2014 broke the other day. It was not great timing. The strange thing was if I cleared the PRAM the Mini worked normally. I had many conversations with Apple who thought it was a logic board failure. I had the following symptoms:
- The startup chime took significantly longer than it should.
- MacOS booted showing the progress bar going so far and then stopping.
- Internet Recovery and normal recovery also failed to start intermittently
I searched high and low across the internet and found little out there. In the end in an act of desperation I replaced the PRAM battery. The battery is a BR2032. While a standard CR2032 does work (I used it as a temporary fix). The BR2032 is a different chemical composition, designed to withstand higher heat and is also the same type Apple used originally. While Apple were right this cost me a few quid compared to a large Apple repair bill.
I wrote an ifixit guide which can be found here: https://www.ifixit.com/Guide/Mac+Mini+Late+2014+PRAM+Battery+Replacement/118534