The display started showing something like snowflakes
I have followed the exact steps of reinstalling the HD in my iMac Intel 20" EMC 2266. However, as soon as I put all parts back in, connected all necessary cables and turned on the iMac, the LCD display started displaying something like snowflakes and lines all of the time. It looks like and old time TV when your antenna is not fixed and you see the picture through snowflakes. Does anyone know how to fix that?
Thank you very much in advance.