Hi, right, this issue has been bugging me and I've been trying for ages to get i tot work! I have a 2010 iMac 27.5inch, that was given to me by my dad as he bought a new one. Always worked fine. When he gave it to me, he asked if I could delete everything on it (As it was his business one) so I followed guides online and ended up wiping the entire OS. Reading more guides, I realised I needed a bootup disk, so bought a memory stick with OSX Snow Leopard on it. However, now, I literally can't seem to get my iMac to show any screen other than the bootup Apple logo. I've spent hours searching the internet, and I've reset everything possible (To no avail) and tried booting in every mode possible. The issue is, when I try and boot in a different mode, by holding down different keys on startup, the screen goes white, and will stay white until I let go of the key, which sends it back to the never ending Apple logo screen. I literally have no idea how on Earth i can fix this? And for the effort and the price, its not really worth taking to the Apple store. Any help would be much appreciated.