Help!!! Imac Gray Screen

[hoggis]

Morning All

I have a problem, am trying to fix a friends Imac that is failling to boot. The systems starts up fine, i get the chime and the logo, the progress bar comes up and gets about half way, the screen fades to black and then goes grey.

I have tried to boot the local recovery and the same happens, i have tried internet recovery (internet shared though my iphone though) it apears to download, restarts, starts loading and get half way, screen goes grey and stops. I have tried booting of a ubs pen drive i have with mac os on it, again half way, goes grey and stops. The only thing i can get to work is the hardware diagnostic which runs and doesn't fined any issues. Any idea's anyone, am out of them.

Thanks

 

[Fishrrman]

What year was the iMac made?
What version of the OS?

 

[hoggis]

What year was the iMac made?
What version of the OS?

It’s a 2011 i5 as for the os, I don’t know and the owner won’t know, he’s is not tech savvy

 

[mikehalloran]

This is a symptom of a bad NVRAM battery—if you’re lucky. Replace the battery with a CR2032. Takes about 15 minutes with a T8 driver—the glass has to come off but not the screen.

If you still have a problem, it can be a number of tings all involving time, money or both. Do you really want to put coin into a 2011?

You still have a HDD in this? If so and the battery doesn’t fix you up, the heat generated is the cause of the GPU problems these have. It can be fixed but, again, do you really want...?
[doublepost=1560703612][/doublepost]

What year was the iMac made?

Was there any doubt on the year?

 

[RyanXM]

This is a symptom of a bad NVRAM battery—if you’re lucky. Replace the battery with a CR2032. Takes about 15 minutes with a T8 driver—the glass has to come off but not the screen.

Although this can be a symptom of a bad PRAM/NVRAM battery, it is more than likely a failed graphics card considering it is a 2011. These are notorious for having graphics cards go bad. I would suggest trying to boot into Single User Mode (hold CMD+S after hearing the POST chime). This should bring you a bash prompt.

 

[mikehalloran]

Never diagnose this without a known good battery. I have a lot of experience with these.

 

[hoggis]

This is a symptom of a bad NVRAM battery—if you’re lucky. Replace the battery with a CR2032. Takes about 15 minutes with a T8 driver—the glass has to come off but not the screen.

If you still have a problem, it can be a number of tings all involving time, money or both. Do you really want to put coin into a 2011?

You still have a HDD in this? If so and the battery doesn’t fix you up, the heat generated is the cause of the GPU problems these have. It can be fixed but, again, do you really want...?
[doublepost=1560703612][/doublepost]

Was there any doubt on the year?

I have found the problem, it is the GPU, £100 to fix, works like new now.