I can't open the back of my columbia sportsware CL-7017330 feet water resistance watch. I need to change the battery.

You need a 3-jaw watch wrench to unscrew the back of the case. Then you can see the battery type. Buy one from anywhere that sells watch batteries.

cl 5017 is not a battery code or size, try bring your actual battery or your watch on watch service centers. they probably have your battery.

Dont do it yourself.. it might break if u apply too much pressure. GO to your nearest watch center and ask them to replace the battery for you.. Its better to spend a little money than to buy a new watch!

Read my tips and tricks how to change the battery.

http://www.columbia.com/timinginstructions

This is because you lost the coil spring when battery change took place. Coil spring works as a conductor to the membrane inside caseback and transmits the signal. If you can not find it, you will need to find your nearest watchmaker and ask for new coilspring.
I am pretty sure that you think you did not lost anything, but I can assure you that you did. Coilspring is very tiny and hard to see when dropped and you can not hear it as well.
In case if you find that spring, you have to open the watch and put it back in. There is a small hole in the watch movement and it is designed for coilspring.

Rate me, please.

Buy a set of precision srewdrivers. Remove back(4 screws),take your 1 mm flat screwdriver and push straight down at the end of the hold down strap at the inside end. KEEP IT TIGHT IN THE NYLON CATCH! The hold down is hooked on the bottom of it. It will release and you will be able to lift that end and replace the battery. Then just push it back to hook it,VOILA! R.J.S.

Are you able to slide the metal casing sideways? I think it should just slide sideways. Good Luck!