Flashing power but no noise

Hi, I bought a wonderboom a few days ago. It seemed to work fine at first but after a few hours the volume kept turning itself up and down. I put it on charge and left it as it wouldn't pair anymore (I thought the battery must just be flat) it's been on charge for a full day and I've just tried to put it on. The power light was just blinking and it wasn't showing up on my list to pair to it. I've tried it with 3 other chargers and tried to reset it but nothing. Now there's no lights on at all even when it's plugged in. Can anyone help or do I need to send it back?

Thank you