After trying to install El Capitan and getting several notices that it can't be installed, now when I boot the computer it seems to be stuck in a login loop or something.
Every time I restart the computer now I see the grey progress bar start as though it's doing something (with Apple logo), it goes for a bit and then shuts the machine off.
I have tried holding Shift while powering on into safe mode, but it has no effect. I cant even boot now, just a loop.
I have also tried using Cmd+R to reinstall OSX 10.8.5 but it says the disk is locked. I chose reboot from 10.8.5 disk, but it simply goes back to the loading progress bar loop.
Was upgrading from 10.8.5. OSX on Intel MacBook Pro