Garmin Instinct solar tactical will not charge

Hey all,

I was out doing some activities over the last few days and while I was asleep one night it looks like the battery ran out and the watch was dead.  When  I got home last night.  I tried to charge the watch.  This is a used watch that I've had for a few weeks and it's been working great.  Decent battery life.  When I have charged it previously, it has ususally charged up in less than an hour. 

Now, when I try and charge it it won't do a full charge even though it's been charging over night, and it seems like it's loosing charge each time I plug it in to try and charge it more.

Also, when I plug it into the computer, the computer recognizes it as a USB mass storage device, but It doesn't seem to want to charge and Garmin Express won't recognize it to sync activities or do updates....

any idea what might be going on and how I could fix it?

Thx.