2003 fx35 door lock problems

35 or 45 , which is it.? typo?
well if it has strut cartridge they are bad
these

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313&_nkw=INFINITI+fx35+rear+hatch+strut+cartriges&_sacat=0

If it opens from the outside, check on the door itself near the latch assembly for a little black lever that moves back and forth...that is the child safety rear door lock and when engaged, wont allow the door to open from the inside...setting the lever to free position should allow door to open (pg 3-5 of owners manual)
https://owners.infinitiusa.com/content/manualsandguides/FX/2008/2008-Infiniti-FX4535.pdf

First check the accesory fuse.

try holding button longer

there is a seprsate actuator for each door/hatch. so it is commen on those for more then one to go bad at about the same time. just look and see if you can see the lock move slightly while tryinng to work it. if so then that is what you need.

need to pull door panel off there is a cable that op. the window they get twisted in motor poss. need window motor..

First, on the rear hatch, there is an actuator. On FX, when you close the trunk, it kind of **** the hatch closed all the way. When you press lock on the remote, this same actuator locks it as well.
Now,
1) when you unlock the car from the inside, go back there and press the button to open the hatch door manually, do you here any noises?
2) Close all doors, go back close to the hatch button and using the remote , lock the car and then unlock the car. you should hear a sound from the actuator locking and unlocking the lock on the rear hatch!

If you don't hear this, your actuator is inop.
Next step would be to check the fuses inside the car, on the left bottom driver side, and outside on the battery compartment.
It might be just a fuse.
If all fuses check ok, your actuator is most likely gone! Not ea expensive fix, just time consuming!

NOW, if you can hear the noises, then something is either broken inside the actuator or one of the cables is loose!
Hope that helps.
Also, what year and miles on your fx?

the solenoid on that door is either shot or something wrong with the wiring..possible it has a fuse for each door but doubtful

I would suspect that is a phillips screw. There may be another one in that area -- maybe not.

Removing this screw should allow yu to remove the door panel.

Check the battery to the smart key. Sometimes its as easy as that.