41CV won't turn on after reassembly. Did I kill it?

[g8241CV]

>Not sure I'd be able to use contact cleaner directly on the key

Highly recommend DeOxit before you do anything more radical to keyboard. I found putting a tiny droplet on the hole and then exercising (depressing/releasing) the key caused the air in the dome to burp out and the DeOxit to be inhaled into the keyhole. Or depress the key, and then coat with DeOxit, and release key to inhale. Only takes a minute quantity to be effective. Mistake: if you repeatedly add the DeOxit, you may even find the fill is too much and the oil begins to migrate out of the key dome into surrounding area. BTDT. For fear of delaminating the keypad layers I burped excess oil into a clean cloth.

Further thought on investigation:

Another path to pursue: carefully inspect all the solder joints on the jumpers from the PCB to the display PCB pads. You're looking for any cold-soldered joint(s) working/worked loose.