Rear door problem

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

Rear hatch is locked or unlocked with a key. (if equipped) • To open the rear hatch, insert the key into the lock, turn it to the unlock position and pull up the rear hatch by pressing the handle (DOOR). You can also lock/unlock the latch (but not release it) with the central door lock system. • If unlocked, the rear hatch can be opened by pressing the handle (DOOR) and pulling the hatch up. • To close the rear hatch, lower and push down the rear hatch firmly. Make sure that the rear hatch is securely latched.

first is diagnosis.
you examine and test it. to see if its electrical or mech. failure.
and once discovered that follow that to logical conclusions.

Needs new spring shocks! I just bought a pair on ebay for $50

at the rear of vehicule look for place that are visuel that it is touching exhaust pipe near suspension
only a guest hope it helps

replace them....?

My back hatch would not open but it appears the lock was sticking and the return spring to the handle is broken. We used the key to unlock the back door and then door opened. Then husband sprayed WD 40 in all the lock holes. Now once we open the door we have to push the handle back down as return spring is still missing but the door opens :) . My van is a 2002 Ford Windstar.

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?

Yes. Your Local Auto Parts Store should Carry these as Direct Replacements. If Not, Sears Carries them.

The rear window has to be completely down in order to move the tailgate! You should be happy that your window is stuck up, unlike mine which is stuck all the way down! I have to completly take apart my tailgate!! If you want to try a trick to get the rear window down, my bronco has a rear window switch right next to the headlight knob, take the 2 purple wires on that window switch, and cross them, if your motor still works and if the wires are good, that should make the window go down!!! good luck, hope that helps!