Chosen Solution
Ok so I have a macbook pro early 2010 15” i5 620m I can get this to boot from an SSD or USB drive but it wont boot from a hard drive, I’ve replaced c9560 and can get to the desktop where graphics acceleration, sound, usb work, full keyboard fine everything as expected. My issue is the dark grey boot screen I cant get it out of that mode and it wont respond to normal keyboard prompts like holding option for boot selection or cmr+r for recovery mode. I also cant install an OS after booting to USB it allows me to do the install but then wont boot from the hard drive or ssd. Drivedx shows a faulty interface cable with errors but after replacing the cable itself I still have these errors. PS the SSD install was done on another machine as I cant install on this one.
My first suspect is your hard drive I/R cable that was not designed for the speed of an SSD. Next check to see if the SSD is backward compatible to SATA II. Most SSDs are only SATA III.
