Q: Hard Disk is Locked when reinstalling maverick.  Turn off Encryption gets no response.  Can't boot.

So my girlfriend spilled a drink on her late 2011 macbook pro.  Keyboard all sticky.  I replaced the keyboard and the computer actually booted and the computer was running ok for a bit.  We tried to back up her data, but eventually got a message that the external hard drive was too small.  Before we could start to select files to back up, the computer started freezing and glitching and we shut it down.

The computer wasn't doing any better with a spare hard drive I had lying around, so I replaced the logic board.  With the new logic board in place, I installed maverick on my spare hard drive and updated to El Capitan.  Everything is working beautifully.  However, she would like to access her files from her old hard drive.

The old hard drive won't boot, it crashes after a few minutes of booting.  When I run disk utility, it is able to verify the disk and verify disk permissions.  It says the HD is not in need of repair.  When I go to reinstall OS X from the recovery menu, after I agree to the terms it tells me that the HD is locked.  I've done some reading, so I've gone back to disk utility and with the HD selected I hold option and select "Turn off Encryption" but it does NOT prompt me for a password.  After hitting "Turn off Encryption" several times, I've gone back to try and reinstall OS X but the HD is still locked.  I've gone into the terminal to try to enter some codes I found online, but it didn't recognize them (I've been typing the codes with an asterisk at the end, though it appeared as if the author was using a tiny star.  Don't know how to do this).

At this point, I think I only have access to recovery mode. I also have a hard copy of snow leopard if this helps.  I really just want to save her photos and videos.  I'm able to see some of the data on the HD in disk utility, and it seems like much of it is still in tact, if not all of it. 

Any thoughts on how to reinstall OS X, get the computer to boot, or back up the data?

Thanks in advance.

Sorry if I posted in the wrong community or category.. Newbie (who tried very hard to find the answer in previous posts before posting!)