Thanks for the update. I am sorry for the late reply, I was out of town all day yesterday and just got back online.
Since your monitor is not readable and the throttle has been bypassed, it is safe to assume the entire controller system is not working and cannot be repaired without spending thousands of dollars.
The serial number is ***** close enough to any US model for me to say for certain the information I have is match to your machine. Grey market machines can sometimes be very different when it concerns wiring. I am assuming it is an "A" model from your description. These machines have a backup mode switch in the back of each armrest. One is for the throttle control and the other is the pump control/PRV.
The throttle control will move the governor actuator (throttle control motor), This is the movement you hear when moving the switches.
The other switch will send a fixed current (through a resister) directly to the PRV solenoid instead of it being controlled by the ECM controller.
Using the backup mode will be your best option to have some pump control without stalling the engine.
The PRV is a solenoid valve located on the pilot manifold in the pump compartment. If you trace the hose from the small pump attached to the main hydraulic pump, it will connect to a pilot filter and then to the pilot manifold. On this manifold is three or four solenoids. The PRV (Pressure Reducing Valve) solenoid should be slightly different from the others. It should have a blue wire marked A768 and a grey wire marked A769 connected to it.
To begin testing this circuit, go to the pump backup switch and place it on manual mode.
Disconnect the PRV solenoid and check for power at the connector on the blue wire, you should have battery voltage (24 volts). If not, check for power at the Backup fuse and to the pump backup switch at terminal #3. With the switch in backup, the power should cross to terminal #2.
Next check for ground at the prv solenoid. Connect ohmmeter to the grey A769 wire and to a good frame ground. If you have a good circuit, the meter should read 35 - 45 ohms. A higher reading (above 5000 ohms) means an open circuit and a lower reading (less than 5 ohms) is a short circuit to ground in the harness.
Next test the solenoid by connecting your ohmmeter to the wires from the solenoid. You should have 11-16 ohms for a good solenoid. If it is higher, the solenoid is burnt out and lower is a shorted out solenoid.
Once you are sure this is working and the engine is still stalling, then focus on the engine power and later, the pump control valves.
The transfer pump can be worn but, it is very important to have the pump's PRV solenoid pressure control working correctly to prevent engine stalling. If you are concerned about wear on the pump, the piston can be removed and inspected by removing the large nut on the side of the transfer pump. Be careful as the piston has a spring in it and the nut will have some spring pressure against it. A small plunger is also inside it and can slide out.
Let me know what you find and if you need further help. I will be glad to help all I can.