Need A Solution for Troubleshootings

Yunes-

Just by looking at the manual, I would say the two problems are related.  On page 23, it says: 

4.9 Rotary Potentiometer Monitoring Input via rotary potentiometers are processed by two channels. Two microprocessor systems read the input via independent channels and compare the results. 

On page 93, the manual defines 807 as:

Potentiometer evaluation is faulty: Master (CPU PCB and Frontcontroller PCB) and Monitoring PCB read different values.

I would say that one of these boards are bad.  You may be able to figure out which one by looking closely at the description and function found on pages 42-45.  

Just me,

T.

One of your rotary knobs has probably failed. Turn all the knobs all the way to left and power on the device. If it powers on without a failure, one of your potentiometers has a dead spot. Then slowly click each knob all the way to the right one by one and see which one causes the error.