Why won't my iMac boot after replacing the hd?

I recently replaced my original hard drive in my iMac Intel 20" (2006) and put everything back together. When I turned the iMac on and put the OS install disc in, the power light comes on, the fan goes at full speed, but the screen does not turn on. I can not even get my disc out.

I have a bluetooth keyboard and tried to hold the "d" or "c" key (can't remember which key it is, because it is printed on the cd that is in the computer right now) to load from the cd, but nothing happens.

I opened the computer back up and noticed that the thermal heat sensor wires came out of the plastic connector to the logic board.

If I bought a new thermal heat sensor wire, could that solve the problem I am having with my iMac not booting up and the fan going crazy?

Any help would be greatly appreciated. Thanks!