Does anyone know how to open the key fob to replace the battery?

 

?? What year?
The FOB with my 01's have a torqx screw, back it out, pry open the FOB.

 

same question on 2015 key fob
no obvious seams to pry apart !

aha!
Used emergency key to pry (lightly) inside fob's key slot enough to crack open the lid, then use a thin but not sharp metal blade to separate lid from fob (think butter knife).
Battery falls out.

However, after new battery was installed i'm getting "key not found" too often unless I put fob in receptacle in dash.

 

I took apart the org key where proximity works and the new one where it doesn't and see they are not same. The one where it works has part number that ends with *66 and has 2 batteries, the new one has part number that ends with *64 and only one battery. so my conclusion is I probably bought the wrong key