I have 3 of these GPIB adapters (have 3 x AM5030B).
I wanted to program the serial number and it didn't work. So I connected a logic analyzer to see what was going on.
If you only want to update the calibration data, you can program the addresses 0xE0-00xE1 (CALC 00 or RinX1 value), 0x0B-0X0C (CALC 01 or RinX10 value) and 0xCA-0xCB (CALC 02 or RinX100 value) in the PCF8570 (Base address= 0xA0) on the I2C bus with "Bus Pirate".
The calibration data are stored there. After changing the battery, 0x61A8 (= 25000) remains there.