Flashing green light on ds lite

Had a Ds lite given me yesterday for my son, once I have turned it off and shut the lid down, after a short while the green light starts flashing. As soon as I open the lid it starts up without pressing anything, having a ds myself I know this isn't normally what happens. It does look like it's had a cuppa spilt on it which I'm guessing could be part of the problem, but I'm wondering if this will use the battery up as it constantly flashes?