Red Apple on boot up screen and system restarts

I've never seen that issue. Could you share a picture?

That almost sounds like a hardware issue...does the hardware on your Mac come back okay...specifically in the display realm? The pic that @bpavlov requested would add good context.

This likely goes two ways: one being some sort of strange hardware issue in your display or two being some sort of error code system I have never encountered personally.

Quick Google search found me this pic from someone else .... is this similar to what you are seeing?https://apple.stackexchange.com/questions/263201/funny-apple-logo-colors-during-startup

This guys issue was a video issue though that Apple support helped him with.

I've seen something similar before, try an SMC reset and/or a PRAM reset

SMC: Hold down shift+ctrl+option and press power for a few seconds, restart normally

PRAM: Hold down Command+Option+R+P, power on and either let the start up chime go 3-4 times or watch the screen flicker (if you have newer Macs without the start up chime), then release and let the machine boot normally.

Good luck!

To dovetail on to @edickson , you may have to disable EFI password to reset SMC and PRAM (and safe mode too).

a red apple is not a standard return, usually a distortion/discoloration at boot implies hardware failure. Also; can you you boot to recovery?

Thank you, everyone,

The first question looks like this: https://apple.stackexchange.com/questions/263201/funny-apple-logo-colors-during-startup
But, it restarts over and over continuously.

I will try the SMC, I did try PRAM, with no fix there.

I will let you all know what happens, fortunately only two iMacs on a single campus and need systems up by the week of the 20th so I have a few days. Thank you to everyone for the help will let the group know what happens.

Good morning, everyone,

Nothing has seemed to work on these two units and they are only a few years old.

I tried both the SMC and PRAM reset. I can try to reimagine and see what happens but not sure that will work either. If it is a GPU issue I will get them to our repair center soon.

If anyone thinks of anything else please let me know.

Have a very great day today!

did you try booting into recovery? booting to a known good operating system (or internet recovery) is pretty much step 1 in hardware troubleshooting issues like this. just hold Option-⌘-R while you power on the machine.

Were the Mac's previously imaged and now updated via Apple's updater?
I've seen a similar behaviour and I got it down to the Mac's being built via the old imaging method.
I'm currently flushing out all the ones setup this way (booting via recovery and re-installing the MacOS or via erease/install command) and quite a few of them recevies firmware upgrades.
Once that is done with a fresh MacOS they behave as they should.

@tjhall These were actually originally imaged with an AutoDMG OSX of Sierra a year ago. I updated them to High Sierra via the Install High Sierra.app. These two iMacs were the only ones that took a dive and gave me the Red Apple. Almost think that it may be a GPU issue, but will try a few things before I send them in for repair.

@balexander667 That was the first things that I did it found no issues in Recovery. I even tried re-installing the OS on one of them and it still Red Apple'd on me.

Thank you all for the information.

Did you ever figure out what was going on? My computer just started this exact thing, today. Your issue is the only one I could find that was exactly what I am experiencing.

Thanks!

I couldn't find a fix and ended up having to erase and image the system again.  Was a real bummer I hate doing that.

Thanks for letting me know.