I've been having similar issues with a late 2011 17" MBP with 10.9.4. I haven't worked out what the problem is, but I'm eventually able to enter recovery mode after multiple (15-30) attempts. Between attempts, I tried resetting the PRAM, entering safe mode, entering hardware diagnostics mode, and occasionally just leting it hang on the blue or grey screen.
Repairing disk permissions fixes the problem. It's happened twice now, with an hour or two of panic between getting it back up and running again. It's only been since the 10.9.3 or 10.9.4 update, which other users have experienced problems with. I didn't make a backup before updating (this is the first issue I've ever had with my machine), so I may have to start with a fresh install to determine if it's software or hardware.