I'm not sure what it could be. I suppose trying to plug the unit in a different outlet would seem redundant, but have you tried that?

If not, it sounds like a repair issue. I have no idea what could have caused that. It could be anything from a power spike to the power supply giving out. It's mere speculation, but that's the best I can do with the information provided.

I wish there was a secret reset button, but I don't have anything up my sleeve that could diagnose this.