I hooked up my 8,1 Macbook Pro's (A) fully Filevault 2-encrypted internal disk (El Capitan) to another Mac B (also El Capitan) externally to back it up. I had to input my Filevault password (every time) to access the disk, ran the graphical disk utility app's first help function on the disk which corrected some minor problem and after backup used diskutil eject to eject the disk (all on Mac B). The Macbook's (A) battery was disconnected for a few hours. When I put the disk back into my Macbook (A) (and reconnected the battery, obviously), there was no Filevault login, just a progress bar. It looks and feels to me as though the Macbook boots the system on the hard drive without the password. The boot does not complete beause my GPU is fried (that problem, yes). Can that be? Did disk utility app do sth. to the disk? Or is the Macbook booting the unencrypted recovery partition although I chose the recognized hard drive from the boot menu? Does anyone have an idea about what might be going on?