We had fuse 20 blow on our Otis Low-rise LVM elevator electrical drawing #ABA21241VM. We found the short in the rear hoistway door latch switch and replaced the fuse. Now the display reads "LOS" and car will not operate at all. The door will open and close with the buttons inside the car but the call buttons do not respond at all. The door open button on the circuit boad will open the door and the breaking the safety light curtain will open the door if it is closing.

We tried the reset button on the circuit board but no change. We cycled the power and the car lowered to the bottom floor and door opened and closed so that worked correct. Any ideas?