2004 cts cadillac trunk will not open with remote or button on drivers door.

Actuator in trunk disconnected or Brocken

your latch is broken

Did you check the trunk relese fuse 15amp location rear fuse box . How did you check fuse's an relay's ? Did you use a DMM - digital multi-meter ? Did you check the elcetrical circuit ? Do you know how a relay work's ? The BCM - body control module controls the trunk release relay . Check for B+ voltage at the relay .
VEHICLE RELAYS Operation Diagnosis

I would check the owners manual or with Cadillac - its possible the remotes lost part of the signal and need to be reset. It sounds like the receiver is not getting a signal from them by using that button.
Could be the receiver too.

There is a fuse box under the right rear seat cushion behind the driver. In that box is a 10 amp mini fuse marked "TRUNK DR RELEASE". That is the fuse that powers your remote receiver. If that fuse is good, the receiver may have failed. To remove the seat cushion, pull the front of the cushion up and then forward.

Open the trunk manually. Pull down the back seat armrest and open the door for trunk access. There is a yellow handle that is above the door, pull the handle and the trunk will open manually.
The remedy for your problem is probably the fuse that runs the solenoid to the trunk opener, it is found under the rear seat passenger side. It has a black cover over it, remove the cover and find the corresponding fuse.

open trunk, remove the plastic panel around the latch plate, remove the plastic mounting bolts that hold the grey trunk liners in place, there are two 10mm nuts that hold in the light remove nuts pull out light twist the bulb retainer out and replace bulb.

if you here a clicking sound when you push the remote or the drivers button then the solenoid and fuse are probably o.k. lubricate the trunk lid catch and operate the latch a few times, also check the tension on the trunk itself , it should lift up part of the way by itself, if not 1. lubricate the hinges and move trunk lid up and down. if still bad 2. if it has a tension rod adjust the rod to a stronger setting if it has gas shocks, 3.replace shocks. if no click and fuse is good solenoid may be bad

Is there a noise within the door when the button is depressed? If so, sounds like a connecting arm in the locking mechanism may have come loose...

With the trunk open try to accuate the button on the driver's door, check the state of the lock in the trunk first and see or have someone watch it if it moves when you push the door's button.

You may also try manually to open the lock right in the trunk.