2017 iMac 3.4Ghz won't boot help

[rycmurray]

So long story short, I'm at my parents house on vacation and I'm trying to help them get their Mac updated and such while i'm here. I had downloaded the Catalina update and it had started to install and it was in the middle of rebooting, but then the power went out. Now when i press the power button i hear the fans spin up and the hard drive start spinning but it doesn't boot. Screen doesn't power on and there is no chime. I called Apple Support and the went over a few keyboard shortcuts, to no avail. I was then told to head to the Apple Store. I spoke with the employee there and he tried the Option+Control+P+R function and it didnt work, based off that he said it was either the Display or the Logic Board which would both have to be replaced. I'm kind of at a loss as to what I should be doing next, it's not under warranty anymore and I'd prefer to avoid buying my parents a new iMac if at all possible (but will if I have to). Any thoughts or ideas on things I should try? Any help is greatly appreciated. Thank you!

 

[TwoH]

You won't get a boot chime since it's 2017. When you try turning it on, and you hear the fan spin - do you get any light on a wired mouse?

 

[rycmurray]

I don't have a wired mouse to test this with, but an iPhone plugged in does nothing. The only thing I got it to do was register the reset with a keyboard (i can hear the fan spin down and the hard drive spin down then all of them spin back up when pressing the shortcut) but it ultimately did nothing.

 

[TwoH]

I don't have a wired mouse to test this with, but an iPhone plugged in does nothing. The only thing I got it to do was register the reset with a keyboard (i can hear the fan spin down and the hard drive spin down then all of them spin back up when pressing the shortcut) but it ultimately did nothing.

From what it sounds like then, I doubt the issue would be anything to do with RAM sadly.. But you could always try to re-seat it.
Do you see any faint image if you shine a light on the LCD when it's on? Either around the middle whilst it boots to see the Apple logo, or around the top, when you believe it would be booted into an OS.

 

[Fishrrman]

1. This is what can happen when you try to "upgrade" without making a proper fully-bootable backup first.

2. You probably need a WIRED USB keyboard (for command-key options at boot).

3. Try this:
a. UNPLUG the iMac from the wall
b. You didn't tell us WHAT SIZE the iMac is. IF it's a 27", take the RAM out for 10 minutes, then replace it. (You can't do this if it's a 21")
c. After 10 minutes, plug it back into the wall and try to boot again.
d. I would suggest that you IMMEDIATELY hold down "command-OPTION-R" after you press the power-on button. (for "internet recovery" -- wifi password may be needed as well).

IF you can revive it, FORGET about "upgrading" to Catalina.
Let it stay where it is!

 

[mjs916]

Try unplugging it from the wall AND the back of the iMac for 15 seconds. Reconnect the power cord and then plug it back in. Wait 5 seconds. Press the power button until you hear it begin to power on. Wait a couple of minutes to see if it boots. It should hopefully start. Maybe give it a couple minutes.

If that doesn’t work then the more complex steps above would be the next steps.

*The extra step of removing the cord from the back of the iMac is something I learned while part of Apple Care. For whatever reason, the SMC reset wouldn’t take until I began doing that even though it’s not listed as part of the SMC reset instructions 🤷🏽‍♂️*