My ds lite won't charge!??!?!?

i plug it in to charge it and the orange light goes on, then after like 3 seconds, the light goes off, i tried plugging the charger into a different socket, same thing, i tried a brand new charger, same thing. i've had my ds for a little over a year. how likely is it that its the battery and not the ds? i bought a replacement battery but i can't unscrew the battery cover because the screwdriver sucks. personal experiences?