Arduino Mega ADK: Stopped working after using power supply

Hey,

Just got my Arduino Mega ADK and wanted to test it out. So I hooked up my phone, installed the software/sketches and tried it out. It didn't work, so I read something about using a beefy power adapter since it needs to charge the phone as well. So I used the 12V - 3amp power adapter I've used before for my Arduino Duemilanove and tried it again. It still didn't work. After a few minutes the lights of the mega suddenly turned off so I unhooked the power adapter and USB cord a.s.a.p. If I connect a USB cord only now it lights up the regular and ON led for a couple of seconds and then slowly dims down untill both are off. Anyone know whats wrong? Can I fix it or should I return it? I was so looking forward to create some awesome stuff with this... :frowning: