I recieved my new watch yesterday and have worn it overnight to try it out. Decided to charge it up to full today and it won't charge. I have tried plugging into two different wall chargers as well as a usb socket on my PC and the result is the same. When I push the cable into the back of the watch it buzzes and shows the charge amount but as soons as I let go of the cable it stops charging. Do I need a replacement device? If so I'm not at all impressed.