DIAGNOSIS You've thermally locked the motor. Making thick, heavy pastes like nut butter without enough oil can cause a dead-stop stall that overheats and trips the internal thermal protector.
FIX Unplug the blender immediately. Let it cool down completely for at least 60 minutes. Once cool, plug it back in. It should reset and work for normal tasks. Never attempt nut butter without significant added oil and using the 'Food Processing' bowl attachment, not the main pitcher.
IF THAT DIDN'T WORK If it's still dead after a full cool-down, the thermal fuse may have blown permanently from repeated overloads. This requires a service repair.
HEADS UP The main pitcher blades are for liquids and semi-solids. Use the included Food Processor bowl with its S-blade for dense, dry tasks.