My dsi won't turn on!

hello i really need help with my dsi, it wont turn on. What happend was my ds wouldn't hold a charge long and needed to charge more often, one day i came home and tried to use it but all it did was flash the blue light. Yes i have tried charging it, no it isn't the battery i tried a new battery in it but that didn't work. so basically the blue light flashes then turns off, the screens don't flash just the blue light. while trying to charge it the light stays on for a few minutes but goes out after a while as if it's done charging but it won't turn on still! please help me O_O