You hit the unlock button on your keyfob and nothing happens. You open the door with the key, manually, and try the power unlock buttons. Still no dice. You may have experienced door lock actuator failure. Back in the day, vehicle locks were intended to be locked and unlocked manually with keys. This is no longer the case. Instead, the locks on modern vehicles contain small electronic devices that enable the locks to be latched or unlatched remotely or electronically.