It sounds like the tumblers might be "frozen" or stuck. Try spraying WD-40 into the lock before inserting the key. Use the plastic straw that comes with the can, insert one end into the nozzle hole and the other end inside the lock. Don't be stingy. Let set a minute or two and then retry the key.
turn the key
how do i replace a trunk lock with another lock that has a key
Put your key in the trunk lock and turn.
If the key doesn't turn at all, make sure you have the right trunk key, i.e. one that worked before. Many times the ignition and trunk key are different. If it is the right key then the cylinder may be frozen. The remote opens the latch a different way. Try spraying some liguid wrench into the key hole and keep trying to turn it. if the works spray silicone spray or lock lubricant to oil the lock afterwards. If the cylinder does turn and doesn't release the door, look inside to see if the inside lock mechanism is broken.
unlock the doors and then push the button on the trunk. If the trunk lock key slot is horizontal you will need to use the key to turn it vertical. Then it will function with the central locking system
Put your Key in the lock and turn it counterclockwise,,,, Push the button and voila.... the trunk lid opens.....
Insert the key, turn it all the way to the left, push the lock in and open the lid. Do the opposite to lock it.
Try turning the key to the left a couple of times on the passager side door until you hear the lock release on the trunk you should be able to use the switch in the back there by opening the trunk
put the ignition key in the little hole in the xk8 emblem on the trunk lid and turn it. works like a regular key lock trunk
With the lock in the vertical position, insert the key, then turn it to the right, when you can not turn it further you push inward and it should pop open. If this does not work then you have a problem with the lock itself.
Use your key to turn the lock on the rear of the vehicle.
use the trunk key and turn it one way or the other in the trunk lock and hold it for a few seconds. This should disarm it.