I've got a mid 2012 MBP 13" in which I inserted a brand new MX100 in the place of the old HDD. I've put the old HDD in a case in the superdrive place and tried to install 10.10 but the install failed.
I then tried with th SSD in an USB case, managed to install & boot 10.10. Then I put the SSD back in the Mac and got the stop sign at boot.
At first I thought it was the Firevault on the HDD which was causing the issue but even after turning it off, the mac didn't want to boot...
Which brings me 2 questions:
- Why does it boot when plugged in an USB case and not from inside?
- How can I fix this thing?