Im having somewhat of the same problem. It was working fine last year and now the only one that worked was my unlock one and now it dont! But when I test the battery it shows it fine. I pulled it apart and the thing that holds the battery was broken so I superglue it and still not working!!! A funny thing is..when we went camping over the summer I got thrown in the lake with them in my pocket...I was like crap! Got out..All of my buttons worked..as soon as it dried off it stopped working! Thats why I kinda figured I was getting a short or something but now I have no clue!
Sounds like there is a short. Water can conduct electricity so its possible it allowed a connection for a short time to allow the remote to work ( yes its unlikely but is possible ).
2004 Pontiac Grand Prix GT - 3800 Bored and Stroked
Stage 1 wing - Custom Tuned PCM (PRJ)
GXP Suspension (Full Swap) - Complete Custom Exhaust