95% of the pin-out is finished. There are some questions still to be answered. Also the models with WIFI, How do they look inside? I would love to see some pictures of the main board in that one!

One guess would be that the un-populated IC nead RTC battery is a SPI flash but not confirmed.

Next important step would be to understand the how the wire sensor works.

P0.0  GPIO Output, Motor Left, Select Forward/Reverse
P0.1  GPIO Input, Dip switch 3
P0.2  ADC6, Motor Right, Current ?? -> Need more investigation
P0.3  ADC7, Motor Left, Current ?? -> Need more investigation
P0.4 + P0.5 GPIO Output, Selector ADC4 input -> accelerometer LIS352AR pin S0, S1.
  0    0 - ADC4 = X
  0    1 - ADC4 = Y
  1    0 - ADC4 = Z
  1    1 - ADC4 = aux (temp batt)
P0.6  GPIO Output, Speaker High volume
P0.7  GPIO Input, ExtInt3 Raising edge - Wire sensor -> Need more investigation
P0.8  GPIO Input, ExtInt3 Falling edge - Wire sensor -> Need more investigation
P0.9  GPIO Input, ExtInt3 Raising edge - Wire sensor -> Need more investigation
P0.10 GPIO Input, ExtInt3 Falling edge - Wire sensor -> Need more investigation
P0.11 GPIO Output, Enable Charging (in charger, after P1.23 is set to 1)
P0.15 SPI SCLK, LCD
P0.16 SPI CSB, LCD
P0.17 SPI MISO, LCD <- Unused? NC?
P0.18 SPI SDA, LCD
P0.19 SPI RSTB, LCD
P0.20 SPI A0, LCD
P0.21 GPIO OUTPUT, Selector Guide Wire sensor, Range / Amplification
P0.22 GPIO OUTPUT, Selector Guide Wire sensor, Unknown function -> Need more investigation
P0.23 ADC0, Charge current? (Or Charge voltage, Only >0 then charging) 
P0.24 ADC1, Voltage Battery
P0.25 ADC2, Accelerometer, Sideways (X/Y)
P0.26 ADC3, Accelerometer, Forward (X/Y)
P0.27 GPIO Input, Motor Rotor, Rotation tick? -> Need more investigation
P0.28 GPIO Input, Charger state? Battery full? -> Need more investigation
P0.29 USB D+, Maybe used for softUART for GPS / External mcu communication
P0.30 USB D-, Maybe used for softUART for GPS / External mcu communication

P1.0  GPIO Input/Output, Keypad matrix Row1
P1.1  GPIO Input/Output, Keypad matrix Row2
P1.4  GPIO Input/Output, Keypad matrix Row3
P1.8  GPIO Input/Output, Keypad matrix Row4
P1.9  GPIO Input/Output, Keypad matrix Col1
P1.10 GPIO Input/Output, Keypad matrix Col2
P1.14 GPIO Input/Output, Keypad matrix Col3
P1.15 GPIO Input/Output, Keypad matrix Col4
P1.16 GPIO Input, Hall Sensor, Lifted
P1.17 GPIO Input, STOP Button
P1.18 Unknown, NC?
P1.19 Unknown, NC?
P1.20 GPIO Output, LCD Backlight ON, PWM1.2 can be used here if motors are inactive. (Pulsing screen then charging)
P1.21 GPIO Input, High then connected to charger and charger is RED
P1.22 Unknown, NC? USB Power on??
P1.23 GPIO Output, Initiate Charger, Keeps charger in RED mode. if low charger shows green light.
P1.24 GPIO Output, Speaker Low volume
P1.25 GPIO Output, Keep high for PCB Power on.
P1.26 Unknown, NC? Sensor?
P1.27 Unknown, NC? Sensor?
P1.28 GPIO Input, Power key, Normal HIGH
P1.29 GPIO Input, Sensor, Rain
P1.30 ADC4, Output from LIS352AR, Selected by P0.4 + P0.5
P1.31 ADC5, Motor Rotor, Current ?? -> Need more investigation

P2.0  PWM1.1, Motor Right speed
P2.1  PWM1.2, Motor Left speed
P2.2  PWM1.3, Motor Rotor speed
P2.3  GPIO Input, Dip switch 2
P2.4  GPIO Output, Motor Right, Enable/Start | Disable
P2.5  GPIO Output, Motor Right, Brake ON/OFF
P2.6  GPIO Output, Motor Right, Select Forward/Reverse
P2.7  GPIO Input, Dip switch 3
P2.8  GPIO Output, Motor Left, Brake ON/OFF
P2.9  GPIO Output, Motor Left, Enable/Start | Disable
P2.10 GPIO Input, EInt0??, Sens Motor? Error?  -> Need more investigation
P2.11 GPIO Input, EInt1 Edge, Motor Right Rotation tick
P2.12 GPIO Input, EInt2 Edge, Motor Left Rotation tick
P2.13 GPIO Output, Motor Rotor, Enable/Start | Disable

P3.25 GPIO Output, Motor Rotor, Brake ON/OFF
P3.26 GPIO Output, Motor Rotor, Select Forward/Reverse

P4.28 GPIO Input, Hall Sensor, Cover
P4.29 GPIO Input, Hall Sensor, Front