DIAGNOSIS The thermal fuse on the main control board has likely blown, often from a voltage spike or overheating. It's a failsafe that cuts all power.
FIX First, eliminate the simple stuff. Test the outlet with another device. Try a different power cord if you have one (it's a standard IEC C7 figure-8 cord). Ensure the cord is firmly plugged into the back of the brewer. If still dead, the internal fuse is the culprit.
IF THAT DIDN'T WORK If you're comfortable, you can check the fuse. Unplug and open the base (requires Torx security screws). Locate the small, glass 15A 250V thermal fuse on the board. Test it for continuity with a multimeter. If it's blown, replacing it may restore function.
HEADS UP This often points to a larger board issue. If the new fuse blows again, the main PCB is faulty. Contact Ninja support; this is a known failure point they may address under warranty or with a repair program.