2010 iMac goes dead c. 25 seconds in.

[Petrock]

I press the power-on button. I get the musical tone, Apple symbol, and progress bar. The progress bar stops in about 25 seconds and 30% across; the screen goes black, and the iMac turns off. Anyone know what this is ?

 

[Cory Cooper]

Hello and welcome.

It could be a number of things:
-No free space on the hard drive
-Failing hardware - hard drive, graphics card, logic board
-Improperly seated RAM
-Corrupted install of OS X

Have you recently had any other issues with freezing, power issues, etc.?

C

 

[Petrock]

No previous issues. I'll check those things you mention, as best I can. Will let you know. Thanks !

 

[Cory Cooper]

You could try running Apple Diagnostics, and startup from the Recovery Partition to check the hard drive with Disk Utility and see the amount free space.

Let us know how that goes,

C