Mac Mini 2012 (Outage Problem - doesn't turn on) - EFI Firmware solution?

I have a 2012 Mini and I know of no Firmware update. You may have a power supply issue which can be changed, however I would take it to an Apple genius location for diagnostics. The other solution is a UPS which I have to preclude any power outage issues.

There may be a way to get a rise out of the Mac, but without hands-on trying different things

and then other things, it's not likely; troubleshooting by rote tends to be busywork at times.

NVRAM or PRAM

Had you tried to reset the non-volatile random access memory/parameter random access memory by using

keys on startup to see if the Mac could try? There should be a startup chime; and ideally you'd hear it three

times while attempting to reset NVRAM; so you have the four keys held down on startup. ~ And this may not

work IF the keys are not held down exactly right, then:

...Sometimes if there is no startup sound, no default bong or chime, that may

mean a cable connector or other power could have failed. Could be as simple

as the wall plug or a power strip; those can be bad after an outage or jolt.

A diagnostic or troubleshooting episode may involve a take-apart, because one

of the issues such as a 'flat' or dead clock battery can cause the startup to fail.

So that involves a take-apart to replace the battery. This is near the power supply

and inside, so most parts come out of the case. ~ See iFixit mac repair guide has

detailed 17-sections, for each repair as clues; examples of what a tech would do.

•Mac Mini Late 2012 Repair - iFixit.com/

//www.ifixit.com/Device/Mac_Mini_Late_2012

These guides are helpful especially for those who have a backup computer to use

so as to not be dependent or pushing to cut corners; and so if the device does

need authorized repair service, one could be found.

In what country or region are you located? Someone may be closer; perhaps at

a university or other non-business who could help in matters such as this.

Sorry to not be of much help; the guides may be helpful as a source of visual info.

In any event...

Good luck & happy trails! 🙂

Who knows. That is why an Apple tech needs to assess the circuit.

May have been a bad connection that was casing the issue

If the clock battery were never changed or replaced with new good one,

the effects from a power outage could easily include the ones you've

noted. Also, original owner of 3+ years may not have replaced it either.

I've almost always used quality UPS battery backup with auto switching

to avoid problems from outages, spikes, brown-outs; get a good one of

at least 1500VKA.

The Late 2012 Mac Mini i7 is a bit different than a 2011 i5 mini; has different

hardware and also EFI version. There was no update; my server edition

shipped with Mavericks 10.9.0 and 4GB RAM, two 1-TB 5400-RPM HDDs.

{Now dual-boots 10.9.5 + 10.11.6, partitioned HDD_1; & has 16GB RAM.}

And is now just a bit over three years since purchase direct from Apple online.

The AppleCare has expired; so I figure the clock battery may be due. Also to

clean the inside with vacuum, avoiding wires and tiny connector bits, helps.

See SMC reset instructions, if step-by-step followed and try to not re-set SMC

because most issues can be resolved short of the final solution. An authorized

Apple service should replace the clock battery and de-dust the inside. Also the

original hard drive(s) may be due for replacement &/or upgrade to mercury ssd.

•How to reset the System Management Controller (SMC) on your Mac - Apple Support

Good luck & happy trails! 🙂