Chosen Solution
I recently upgraded my MB pro with an SSD to replace the old HDD. Everything worked fine, so I decided to replace the optical drive with a larger SSD for storage purposes. I started having problems with no drive being recognized at start up and just getting the folder with a question mark on it. Booting and holding Opt-i didn’t bring up any of the drives. I removed both drives and I’m able to boot the computer if they are connected as external drives using the Opt-i function on boot. I’m thinking that maybe the cable that connects the drive to the board is bad, but also concerned that neither SSD is being recognized when both are connected internally and the Opt-i on boot is used. Any thoughts are welcomed!
While a Mac will boot from any type of formatted drive with a system on it externally, if it is not formatted GUID on this model, it will not boot internally. Check your format type when you have it mounted externally and use Disk Utilities to re-format it correctly. UPDATE I would replace the Hard Drive/IR Cable with the one from the 2012 machine, you may have to alter the retainer bracket: MacBook Pro 13" Unibody Mid 2009 Hard Drive Cable Replacement MacBook Pro 13" Unibody (Mid 2012) Hard Drive Cable
