My iPhone 3GS won't work unless it is plugged in?

After I replaced my LCD, my iPhone 3GS only works unless it is pulgged in. Anyone please help and I had the phone in a few months

It sounds as if you may have to replace the battery too… Or while you had it apart maybe it got disconnected…

I'm not 100% sure, but I think there's a problem with your battery. Because the charger charges the battery, and the phone works with the battery in place.

It's basically too old. Get a newer iPhone if you can.

Truthfully that phone is outdated, a lot of smartphone companies (apple especially) stop sending the updates needed to keep the phone working properly so that way it promotes upgrades to newer phones. No matter what you do it's going to get worse so your best bet is to get an iphone 5 and sell that one as soon as you can while it's still worth something because the longer you wait the less it's worth.

The battery is stuffed