BSide Z1 Pen DMM out of spec

[runni]

Hello, I have a Z1 here that always shows 20? digits too little at DC measurement. So at 1V shows 0.8V and at 10V shows 8V and so on.  The EEPROM 24C02 I have unsoldered and read out, as well as the values for the DC calibration set to default. This had no effect at all. Analog seems to be ok, 1.24V Ref. and at 1V input 100mV on ADC PIN.

Is there anyone who has disassembled a Z1 and can provide the EEPROM content? Or an idea how to start the calibration on the DMM itself? Thanks, yes the Z1 is super cheap, I like the form factor, for quick measurements in the circuit.

THX & Best wishes, from Munich.