What I'm doing wrong

I constantly get negative values of measurement. And next value is always linarly smaller then previous. What I'm doing it wrong?

Second question. How to properly search for load balance. My process is this.
- put scale in config mode
- put a wooden board on scale
- put some weight on scale
- browse with browser to UI
- Search for WIFI - save
- sync time, set 1 minute interval, save
- put motor on position 5000 or more
- after it reaches 5000, press button search for balance
- after that, tare, tare, tare, and remove config jumper.

Is this ok? Should I search for balance multiple times?

How should scale operate when the motor reaches position 0 or less. Should it move up slowly to 100, 200, 300 and then back again?

Please advise