Black iMac screen

Hi!

To get more details -

try adding a test user account

Add a user or group on Mac - Apple Support

Sign in with test user, see if issue remains. If not, it user-specific, and not system-wide, meaning, it has something to do with your account.

If system-wide, occurring in both your account as well as in the test user account, we may need to walk a different path. For now, I am assuming it user-specific.

If so, check all settings, energy, battery etc.

Save energy on your Mac - Apple Support

If this is not a setting, restart, if Intel try safemode

Use safe mode on your Mac - Apple Support

or M1/2 follow silicon.

If this fails, please contact applecare to help you "reset homefolder permissions" via Terminal.

Kind regards

RRD

This forum section is for ancient iMacs made before 2006. Is yours really that old??

Because iMacs have been in continuous production since 1998 in five broad families with very different troubleshooting steps, it i s vitally important you indentify your iMac sub-model here. We are other end users who can neither see nor touch your computer so , without sub-model details, we re unable to help in this setting.

As the computer won't start, you may be able to find the sub-model by serial number using this Apple support coverage page:

https://checkcoverage.apple.com

Otherwise post a picture.

Don't feel bad, Apple has the worst way to select where you post of any forum I've ever seen.