iMac mid-2011, 2.5 GH, el Capitan

My iMac has a problem. Here is what it does and what I've tried:

• On startup, I can log in and then it freezes,
• In Safe Mode, I can log in and it freezes
• In Restore (command R), I can get the choices to use Time Machine, Reinstall Lion, and the other two...but I can only choose one, then when I click on that option the screen freezes again.
• (Prior to this issue, I tried to Reinstall Lion using the Restore function but when it took me to Apple Store it said Lion was no longer available. That is why I purchased Lion 10.7 on a thumb drive...I hadn't used it before trying to solve this problem today.)
• If I use Option and choose my startup...1) the Mac Hard Drive freezes, 2) I have 10.7 Lion on a thumb drive and if I try to boot to that it freezes, 3) I have the backup on Time Machine and the boot to that freezes.
• I have reset NVRAM (Cmd + Opt + P + R)
• Reset SMC
• I have recently installed a power supply and SSD with the help of OWC, had not problems for about a month.
• Tried different keyboard and mouse, normally I use bluetooth.