If Root does not charge when plugged into an outlet, try a different USB charger from a phone or iPad. Root uses a USB Type C charger. If your robot has been sitting for a few days or weeks, there may not be enough power to light up the charging LED when it's first plugged in. Plug it in and wait an hour, then unplug and plug in again. If the LED still doesn't light up, leave it plugged in and repeat after another hour.