Macbook pro locked/disabled
This lock is by design. It allows the owner to prevent anyone that can’t prove they own the hardware from getting Apple or other service professionals to erase the lock. 

See https://www.apple.com/icloud/find-my-iphone/ and especially the Mac link at the bottom. 

You now have a firmware password on that Mac preventing you from changing the OS to boot from other sources. You can either enter the passcode that was created to lock the hardware or follow the normal process when you forget a firmware password by seeking authorized service. 


https://support.apple.com/en-us/HT204455