I can't open trunk without the door key. When I push the trunk utton while sitting in the car, switch energizes relay but no power to trunk lock. It doesn't work when I try it on my key fob either.
Fuse problem? What fuse? Or possibly another problem?

 

If the relay is being energized it's not the fuse. The fuse for the Keyless Entry system operates the WHOLE system. So if your other doors are locked/unlocked by the key fob, I would imagine there is a problem with the locking mechanism at the truck. since almost all Neon's came with the automatic trunk, I would get a used one at the junk yard.

 

this happened on my neon too
the lock solenoid gets weak and doesnt have the muster to unlatch the trunk lid anymore

 

what did you replace?

 

the lock actuator, its on the backside of the key cylinder, in the guts of the decklid

 

I wish I had an electric trunk latch... I have an SE model and am pretty sure none of the SE models had an power anything... no locks , no trunk, no mirrors, no cruise
.. and can find no electric trunk latches at the junk yard either... mostly all 1st gen Neons

 

We just hit the piece on the inside of the trunk... & it started working.

 

It's amazing what a hammer can do...lol