Hello all! I have a mid-2011, 21.5" iMac. If I turn it on it starts up to the screen with network, recovery and hard drive options. None of them work. If I click either of the drives it continues for a few moments, and then there is some 'static' in a band across the about an inch of the screen (logic board problem?), and then restarts, and then nothing, just grey. I can't start in safe mode. Resetting NVRAM does nothing. I have no peripherals connected and I removed the additional RAM. I initially thought it was a hard drive failure, but I can access the data in Target Disk Mode. I have plenty of backups etc... In diagnostic mode I get a different failure each test, such as: 4sns/1/40000000: TAOP-52.308 How can I diagnose the problem? Thanks!