Grinding noise from inside the door (lock mech)????
Can also help if you let us know what make/model coach you own.
My 07 Fleetwood has a remote to unlock/lock the door. Actual "box" is in between the fron seats (under the radio). Also, on the entry door you can see three pins/contacts. Those connect the locking mech when door closed. Needs to be clean.
It sounds like a mechanical issue meaning it "might" need to be replaced.
Again, let us know what make/model RV, others might have an idea whats going on.
RM