A couple of notes:
- Be sure to remove all of the components around the edge of the trim that were trimmed though. Having half-components still on can cause shorts / other weird stuff.
- All of those joints look very cold. Make sure that your iron is set to a good temperature (I usually keep mine in the 650-700F range), you have a good tip (a chisel with a large, fat surface area to make contact with the pads is good), and are using good solder and plenty of flux. The combination of those things should lead to some better joints.
- I would recommend against having the PMS sitting on top of the Wii like that. Using electrical tape on both would work, but would be pretty sketchy. Electrical tape ends up breaking down the adhesive residue just gets all over everything... plus it would be much better to have some kind of secure mounting system for all of your boards. Better than having everything floating around in the shell. Maybe you could 3D print some kind of skeleton to mount everything on, then epoxy that into the gamepad? Just spitballing...
- Did you check your resistances between your voltage rails on that trim prior to connecting it to the PMS? If not, I would undo the PMS joints (which you'll do to clean up the joints anyway) and check those before applying any kind of power to the board.
- 4LayerTech sells RVL-NTC replacements on their site.