Removing battery/Tuner problem in Takamine with CT4-B preamp

[valleyofmalls]

I have an EAN-15C and the tuner has started to not work intermittently when I press the button (no red light comes on) and I have what seems to be a fresh battery in it. It worked for about 2 minutes at one point yesterday, but it hasn't worked at all since. The guitar works fine when plugged in though.

 

Any ideas or help would be appreciated!

 

Also, when trying to remove the existing battery, I can easily pop out the battery holder, but am having trouble getting the actual battery out of the holder. What do I need to do?

 

Thanks!!