My trunk is stuck shut, how can I get it open? I can hear the lock mechanism unlatching using both the key fob and the latch by the drivers seat, but nothing is happening.

Let's troubleshoot this issue:

Valet Mode:
First, check if the trunk is in valet mode. Some vehicles have a setting that prevents the trunk from opening using the key fob or the dash button when in valet mode.
Look under the trunk at the top of the license plate area. You'll find a key slot there. Use the physical key section of your key fob to open the trunk manually.

Child Locks:
Ensure that the child lock feature is not accidentally engaged. If it is, the trunk won't open from the outside handle switch.
Switch the child lock to the unlock position and try pulling the trunk handle again before closing the door.

Trunk Release Relay:
If the above steps don't resolve the issue, there might be an issue with the trunk release relay.
Check if there's ground at the switch in the glove compartment when you activate the release switch on the door, the trunk release on the key fob, or the rear handle.
Use a paperclip to jumper between the #30 and the #87 pin sockets of the relay. The pin numbers are usually labeled on the relay body.

Mechanical Issues:
Inspect the trunk latch mechanism for any signs of damage or obstruction.
Verify that the outside trunk handle is properly connected to the latch.

Hyundai azera trunk unlock Switch (youtube.com)

If necessary, consult a professional mechanic to diagnose and fix any mechanical issues.
Remember to follow safety precautions while troubleshooting, and if you're unsure, it's best to seek professional assistance.

Sorry, but the seat release in the trunk. So you have to pull the bottom up an out. then remove the bolts that hold the back down. then lift it up to to release it. If the seat belts go threw it, then you need to have some one hold it as you go threw it . when in the trunk there is a yellow handle to pull to open the trunk. Once it is open you have to remove the latch, then remove the key lock. First modify the lock to fit your key or buy another one. then you need to find out why the latch doesn't work. This could be the latch, wiring, BCM, or the switch. Most importantly, is that the key works.

Valet Key ? 0nly does the drivers door & ignition

A problem I had with my 2003 BMW was that the wiring near the trunk hinge that feeds the lock mechanism had been bent back and forth enough times (I open my trunk several times a day) that some of the wires broke. The only way I could get in the trunk was by the mechanical key. The fob and the button release in the cabin did not work. I was able to access enough wiring before and after the hinge area to do a continuity check on the wires and at least a quarter of them had broken. Later I realized that the third center brake light (which is on the trunk lid) was out too. After some patience of unraveling all the wiring I was able to reconnect everything ... but it took several hours....
In your case I do not understand that your latch will not open. Usually if it is set in the lock position when open ... you can stick a screw driver in the mechanism and rotate back the engaging hook which then stays in the open position until you close the trunk again.
If that is not the case with yours, then the mechanism may indeed be toast.
Helpful?

In my '04 corolla I can unlatch the left passenger seat back by reaching behind the left seat back and sticking my finger up into the second of 3 quarter sized holes. my arm is about 15" stuck in and reaching up into the trunk about 6" back. Feel around for the holes. You can pull the latch at that point, but...you have to be flexible.

This can be cause by one of two things....

#1 The latch isn't lining up with the lock. Look closly at the lock assembly as it comes down on the latch the insure that enverything is going where it fits. If not use a screwdriver to pry, or soft blows with a mallet to move the latch.

#2 The lock isn't open. Look inside the lock as you use the key to open the trunk. Now with the key turned as you would to open the trunk, make sure the latching mechanism of the lock is open to allow the latch to slide into place. Use a screw driver to open it if it is stuck. A little WD-40 will cure it is this is the problem.

Good Luck

With many cars you can go through the back seat in order to unlatch the trunk lock with a screw driver, though I believe the Sentra has a rear seat reinforcement panel that has much smaller openings. I read where you wrote you have the "same problem" though we do not have the ability to see what you have seen and made that comment on. If you please, let me know more specifically the initial problem that you identified with.

Regardless, if you cannot open the lock with the key, then the lock tumblers have probably failed. It is quite possible someone may have tried to break in your trunk, ruining the tumblers in the mechanism. You need to replace the trunk latch. It is rather unusual that it would have failed on your car - it is only 9 years old.

Trunk latches have varying degrees of difficulty with regard to installation, though if not mechanically inclined, a repair shop may not charge more than $20.00 to install. This is, however, simply a guess as to how much you would be charged. You would do well to spend some time with your local yellow pages. Price the lock through Nissan, and compare repair shops to Nissan's repair facilities.

Good luck, and thanks for using Fixya

Your latch may be broken go though the trunk though the back seat. Check to see if the latch is broken; or stuck. There is a little hole where all you have to do is use a screwdriver turn clockwise if trunk opens then your latch is either broken or your locking mechanism is stuck. Good luck and hope this helps you.

I was able to unlock my trunk by using a wood pole to operate the interior safety unlock handle, which is located just above the trunk floor, against the rear of the trunk lid. You simply insert the wood pole between your rear seats, while attempting to locate the handle release. When you find the handle, use the wood pole to push down on it.

Then, I had to take the top of the truck mat loose by using a flat head screwdriver to pry the plastic plug holders loose from the trunk. I also had to use a 10mm socket to loosen the trunk locking mechanism. Once inside, I notice the remote release cable ball had dislodged from its slot. I simply placed the ball in its slot and reassembled the trunk.

Problem solve. :)

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.