ViVosmart 4

Hi,

I have recently decided to start using my Vivosmart 4 watch again.  After updating the software and charging my watch I cannot get it to turn on.  When the watch is attached to the mains it works fine but as soon as I unplug it, it turns itself off. When I re-attach to the mains it has cleared all settings and I have to start again.

What am I doing wrong, can anyone help, or do I need a new watch?

Thanks