Only LED #1 Turns On Late 2009 27" iMac

[kevinakerberg]

Hi everyone,
I received a 27" late 2009 iMac from a friend who said it wouldn't start. Upon taking it apart and investigating, I found that several internal cables were broken and the video card was loose. After replacing these cables and reseating the video card (also had to add RAM) I tried to turn it on and the fans will spin, however no signs of boot up and only the #1 diagnostic LED is lit. Any help is appreciated, thanks.

 

[mikehalloran]

Did you replace the NV RAM battery? It’s on the back of the motherboard on a late 2009–2010. If running an SSD, you can use a CR2032. If an HDD, use the high-heat BR2032 as Apple did.

 

[kevinakerberg]

I did not, I’ll give that a try. Would that really stop the machine from booting?