Try a couple of basic things first.
Maybe the battery isn’t in quite right. Get a little screwdriver, open the back–don’t lose the screws–and take out the battery, wipe off the contacts if they don’t look clean, and snap it in. It’s just like a cell-phone battery, very easy.
If that doesn’t help try using different USB ports on your computer. Some get more power than others–the back is usually better. Don’t use a hub or anything with multiple ports. Put the cord directly into a port on the computer.