Is the battery an automatic or a manual?
To troubleshoot the issue there are a couple possible issues.
1. The electric components are bad/faulty, and there is no real fix. Believe it or not there is a small circuit board inside!
2. Your switch is sticking in the on postion.
Let me first start off by saying the
batteries are not serviceable/rebuildable! You should not attempt this unless your name is Adrenalyn!
For a manual the "switch" is an external button. This can be sticking after being depressed, resulting in the unit to stay on.
No real fix here except to check the button alignment and make sure it is not rubbing/hanging up on the body when being depressed.
If there dirt/grim around the button you can try an alcohol wipe around the button, but I would only advise that as a last resort as it can cause more harm then good by getting alcohol inside the unit.
For auto batteries,
The switch is a vacuum sensitive switch. When you suck on the cartomizer it pulls a diaphragm with a center metal post toward the end of the battery which makes an electrical connection. It sounds complicated, but it's really not. Really the only way to see one is to dissect a battery.
The switch can have dirt/debri buildup causing the switch to stick.
This switch can be stuck or misaligned. Look at it under a REALLY bright light and you should see a silver little circle (top of the post) in the center of the battery hole.
If that metal post is not centered you can try to realign it, but I must warn you that membrane will break if ANY force is put upon it!
You can also try blowing into the battery WITHOUT a carto attached and see if that recenters the post.
I've also used magnets to recenter this as well. Just don't use a really strong one!
Alot of users have had issues with sticking batteries. I'm sure this is due to natural wear and tear and the fact that ecigs are not super durable.
I do know that Steve and the gang at V4L are among the top in customer service in this and any industry!
Give them a shout and I'm sure they will take care of you to keep you smilin!