Can't get past the system lock PIN code

I locked my MacBook using Find My iPhone and now when attempting to start using it again, I cannot type my PIN into the unlock section. Nothing happens. I can't even click on sleep, restart, shut down or the internet options. I tried Command-Option-R and Command-Option-R-P. Both just came up with a different password screen which I put the PIN into and then they went back to the PIN screen. I have no idea what else I can do.