Recharge the battery, start checking the ground points. Once the battery is charged, check the terminals at the battery to make sure they're tight. Had that happen once on a new battery within 35 miles, it went totally dead. What I thought was a tight connection wasn't really tight, needed to add a washer to the terminal connection to actually make it tight. The bolt was bottomed out but not really holding the cable as tight as it should have been.
After all that, put a meter on it while it's running and check the battery voltage, it should be over 13 volts, typically it will be 13.5 or higher though.