Bigger hammers, smaller cameras

[David Graves]

A newly acquired Canon Demi ee17 suffers the bane of older rf- and non-rf-cameras.....the stuck battery cover. Liquid wrench didn't loosen anything. Vinegar, ammonia? Don't want to hurt the little thing...

 

[btgc]

try vinegar, should work.
Lynx IC versions suffer leaked battery syndrome and vinegar bath is suggested method.
http://www.yashica-guy.com/document/lynxfix.html#five

 

[ZeissFan]

Try holding the coin with a pair of pliers.

You can always try the old trick of tightening to try to break the corrosive bond and then loosening. Of course, this might simply tighten it even more.