Possibly Bricked 2012 Mac mini

[bluewooster]

Hi - wondering if anyone has any advice on how to salvage my precious late 2012 quad MM?

I foolishly tried to install Windows using Bootcamp without doing any pre-reading. After creating the bootable USB, the computer restarted.

Unfortunately, it is now trying to boot to the Bootcamp partition but unable to install Windows from the USB so I get "No Bootable Device - press any key to continue" displayed.

The problem is that my keyboards do not appear to be recognized (I've tried two USB keyboards in every port and a wireless keyboard). So, I hear the opening chime when I turn the MM on but am unable to boot to Recovery mode, Startup Manager, reset the PRAM, etc. (i.e holding down option at boot time will NOT bring up the startup manager). I think I was able to reset the SMC by unplugging but that didn't seem to make any difference either.

Out of frustration, I removed the hard drive, put it in an enclosure and mounted it on another Mac. Initially, I tried to complete the Windows install but was unable to install to the USB enclosure. Finally, I erased the whole hard drive, reformatted, and did a fresh install of Mac OS to the hard drive. I then put it back in the MM and......it is still trying to boot to the non-existent Bootcamp partition! (with the "No Bootable Device" message).

Based on googling around, I have tried a variety of keyboards and USB keys (making sure to use USB2). I have also tried creating a bootable USB Windows installation with UNetbootin (as I've read that the 2012 MM can only boot from a physical DVD) but that was still unrecognized.

TBH, I was planning on buying a new MM at some point but it is frustrating to think that this perfectly useable computer (in fact, faster than my 2019 MBP!) no longer works due to a software issue! I've long given up on trying to install Windows but would love a way to reinstall Mac OS and use the computer again...

 

[niteflyr]

Two things come to mind.

1. Try booting from an external drive. Did you try booting from the HDD externally after installing MacOS on it, before re-installing it in the mini? If it does boot externally, this leads to number 2 which I learned this the hard way.

2. When reassembling the mini it is easy to accidentally dislodge the HDD sata cable plug. This certainly will give you the "No Bootable Device" message.

 

[jrgl050]

2. When reassembling the mini it is easy to accidentally dislodge the HDD sata cable plug. This certainly will give you the "No Bootable Device" message.

This is what happen to me when I put a SSD in my mini and I received that msg. I opened the mini reattached the sata cable plug and everything was back to normal.

 

[bluewooster]

I was able to fix it - I was doing two things at the same time so I'm not 100% sure which did the trick (and I'm not going to repeat the scenario to find out!) but I think the problem was that my 4k monitor was not displaying the Startup Manager and, because I was holding down the option key, the mini was eventually trying to boot to the non-existent Windows partition. So, in effect, I was just holding the option key too long. (maybe)

Even though I could see nothing, I waited for the chime, held the option key for about 5 seconds. Then I pressed the right arrow and enter (as if I was selecting a startup disk). I didn't think anything of it as there was of course no response but, about a minute later, it suddenly booted into the installation drive I had created!

The other possibility - I had read that holding menu on an Apple remote during boot up will serve as an Option key and take you to the startup manager. I was fiddling with an old Apple remote at the time (so perhaps that put it into the Startup manager but the remote wasn't paired to the Mac mini so I'm doubtful).

At any rate - crazy! Turns out I deleted my hard drive and removed it from the Mini (about 5 times in total!) all for nothing. But at least it works again - 90% through the installation now.