Trunk wont open on a 2000 mitsubishi diamante with key, remote nor latch in driver side. how can i get to trunck through backseat?

Would you please describe more details about the failed attempts to open the trunk? When you push the trunk release button. Do you hear the solenoid click? When you insert the key into the trunk. Does the key turn all the way? If so, do you hear a click? Does the key have normal resistance as you turn it or does it feel loose like the linkage is disconnected? Your car should also have a trunk release cable. The lever is on the driver's side floor, near the rocker panel and next to the gas fill door. Please let me know what you know and we will go from there.

open the trunk through the back seat

If the actuator mechanism is functioning (you hear the click) the next step is to see if the cable is connected to the latch. Open your trunk and press the button - watch what happens. You may have to manually 'lock' the trunk with the trunk lid open to observe the action. You can always unlock this latch with your key if necessary.

Let me know what happens ... good luck

Thanks for using FixYa.cop

All newer vehicles have an emergency manual trunk release inside the trunk.

This should be basically a rip cord directly attached to the trunk locking mechanism. Most modern ones have a yellow handle on the ceiling of the trunk that will release the trunk latch if it is pulled. Yours may be a different color, but if you get in there with a flash light you can probably trace a steel wire from the trunk latch back to some sort of handle that looks like you can pull it. Its definitely worth a shot.

pull the back rear seatand try to get into the trunk, they usually have a tab that you pull it and can open the trunk, most likely a broken linkage

You will have to get in the trunk through the back seats, and try and unbolt the latch catch off of the body. Then you will probably have to change both parts if you cannot get the catch out of the latch.

Sounds like the trunk latch actuator is out.

Open the boot with the key and ask someone to activate the lever while you have a look on the latch in the boot. You should see the cable moving if not, it might be broken or just disconnected.
Cheers.

Check the release solenoid for power, open the trunk and have someone press the remote release button, does it make a kind of clunk noise at the latch area? If not check the fuses and the power to the release solenoid in the trunk.

I have a corolla 2003 and I had the same problem. I turned the key to the left and the lock turned left, engaging the valet parking mechanism. I could not turn the key to the right and could not get access to the trunk because the lever next to the driver seat was disengaged.
The way I solved this problem is as follow:on the back driver seat I pulled the back seat forward to leave an opening and snick my arm in the trunck. Then I grabbed the cable used to latch the seat and I pulled forward, i.e. toward the front of the car. The cable is connectred to the trunck so that it can be disconnected easily if pulled towards the front. If you pull towards the back it will remain attached to the trunck. So grab the cable an pull towards the front, and it will release itself. Since the cable is flexible, you can pull it out of the trunk from the same the opening you put your arm, and then disenagage the driver back seat. Fold forward the back seat and get into the trunk and use the lever in the latch of the trunck to open it. The turnk will open.

If the lock does not turn, you need to disconnect the lock from the mechanism, so that the driver seat lever can start working again. To do this, and with the trunk open, remove the cover holded by nine plastic pins. Do not break the pins. After removing the cover, you will see the lock holded by two nuts. Remove the nuts with a rachet. The lock will be loose, and disconnect the lever that connects the lock to the latch. At this point the driver seat lever will start working again. Close the trunk and verify that the driver seat lever opens the trunk. Now you can open and close the trunk , and have time to call the dealer for a new lock.
Good luck.