iMac Intel 20" EMC 2105 and 2118 Power On Button Replacement

To get to the power button first remove the hard drive fan as seen in other guides.

This is a picture of the button in place with the connector to the logic board removed.

There are three plastic pins protruding up from the main back case that the button fits over. They appear to be slightly melted and mashed to hold it in place. I used a pocket knife to pry it up and off the posts.

Here it is with the back plate of the button pried off. This exposes a white plastic washer under it.

The center of the washer has a center locking pin to correctly place it on the back of the button. The washer is concave and the concave side faces the button, This gives the button a spring to it so that it will pop back out.

This is he back of the button that will now just push out. Picture #2 is with the button removed.

Test the button to see if it works.

After replacing the button, use something (like a low temperature soldering iron) that will melt the tops of the white plastic pegs to secure the button in place.