New battery, ran fine, today will not even click

Last week I tried to start it, an'01, and only got a click. Gauges came on but it didn't turn over. Put a new battery in it and it worked fine! I drove to Colorado from Wisconsin and got back on Sunday. Today, Tuesday 5/28, I get nothing! It has been on the charger for over 6 hours (I thought something was left on) no (still) I get nothing in park, neutral or anywhere. The widows do not work, there is no click at the starter, nothing. Everything worked fine for over 2000 miles. What now???

 

All the cables tight, including the grounds?

 

Was the battery light on? Have you checked the alternator? And good grounds? All relays? Starter connections?

 

Installed a new interstate agm battery.. stone dead 3 days later.. my point is double check the battery