348 door locked, won't open...

On my 348 the passenger door stays locked and won't open. Any suggestions. The lock is not broke, I can put the key in and turn it but it won't turn all the way. The same goes for the lock knob, it pulls up but not all the way. I can hear the power locks working but it is like the lock is hitting something - not allowing it to unlock all the way. Thanks in advance

Dan