The problem started on Sunday when we found out that the rear hatch did not lock.We kept trying and discovered that the rear hatch does not lock or unlock from the inside door locks or when using the remote.The only way to lock it is to manually put in the key.When l put my ear up to it, there is no noise when locking or unlocking, so is the actuactor dead?What exactly is the problem and how can l fix it?

The locking mechanism is a tiny solenoid. The solenoid might be defective and can be easily replaced. If you have any mechanical skills, you could remove the interior trim around the rear hatch and replace the solenoid yourself. Or you just might get lucky and wipe the actuating mechanism clean and spray a little WD-40 on it and everything would work out fine.

First try lubing the heck out of the latch, it may be siezed. It may be the tumbler is loose as well.