How do you get the back of the Columbia Sportswear CL7017 off to change the battery?

You can remove it with a pocket knife and it will pop out but the problem will be putting it back and that is only done with pressure that is put under a machine.If you go to a flea mkt they will do it for $5-7.00 for the battery and the cover pressure is free once the battery is changed.So make sure you get a good long time warranty battery so you dont have to change the battery frequently.