“Too High Load” means the controller is requiring too much current attempting to bring the turbo up to full speed.
This could be caused by:
Have you leak checked your system to eliminate a leak as the root cause?
Can you hear the pump starting?
You can use a screwdriver or wrench like a stethoscope to listen to the pump rotor (one end at your ear one to the pump casing).
If you hear no noise at all, you should drop the pump and check to see if the rotor spins freely by hand (carefully - wearing gloves).
If the rotor doesn’t free spin (or visibly damaged) it is a mechanical failure of the pump.