there is a flip switch at the bottom of the handle that allows it to go into coast mode. for manual moving.
but the handle being hard/tough to raise and lower might be due the spring in the bar.
if the switch for coast isnt on you might have a broken wire. either in the handle bar itself(there is a wire that runs through it so it one of the spring broke it may have damaged the wire)
also there is a switch underneath where the bottom of the handle is near the top of the motor. might have a broken wire there or a lose/bad connection.
hope this helps.