Hi, I need help! Please! My iMac won’t boot. It is stuck on the loading screen with the progress bar at 100 but won’t go any further and have left if like that for days. I have check the drives with disc utility. I have reset the PRAM/NVRAM and selected the boot drive again. What I can’t do is boot into safe mode. I tried holding down shift when I boot till I see the apple logo, I have tried holding down the shift for the duration of the progress bar (8 hours still hasn’t loaded - used a book to hold the shift down ) Does anyone have any ideas at all as to what I could try next?