Hi, my Home Mid 2010 iMac from what I’ve read so far, is giving me a strange situation. I was using a 1TB WD hard drive to boot from (internal HDD died), and since 2 weeks ago it worked perfectly. Now it won’t boot up. Progress bar and apple logo appear but it will stay there forever. Sometimes progress bar advances 100% and sometimes just a bit. I blamed the bad HDD so I removed it from iMac, but problem prevails. But if I used the same USB ports with a DVD drive it would boot from Snow Leopard DVD OS disk and let me do a fresh install of Snow Leopard booting up as many times as I wanted. But if I upgraded to El Capitan (only OS available at app store) then problem would come back.
I then went ahead and prepared (at works other good iMac) 3 HDD’s with a fresh High Sierra OS: a 100Gb 2.5 Sata, a 1TB 3.5 Sata and a 120Gb 3.5 IDE. All disks verified, repaired, tested, good and booted from on work’s iMac.
Last night I placed the 1TB as an internal HDD and problem prevails. I even ran Command S and booted up in Terminal and run FSCK -Fy which found no internal disk errors, all seemed to be OK. Im leaning now to a possible problem on logic board, but from what I read mine does not have the tell tale signs of a bad logic board: mine chimes, boots from command-S, -V, option(choosing any other disk/device connected) long beep if there is no RAM, and has visual display (apple logo and Snow leopard running good), so Im really at the end of my wits.
What could be possibly wrong?
Cheers!