BQ34Z110 data flash error

The error code mean "no response". Can you check to see whether the gauge is sealed as this would cause the error when trying to read the DF? Check to see whether the FAS and SS flags are set. You could also see this error if the gauge is in ROM mode.

yes. I can see 'FSS' and 'SS' flags. How to chage unsealed access?

The process to unseal the device is in the EVM User's Guide. Here is an excerpt.

Ensure that the gauge is in Full Access mode. The SS and FAS flags in the Control Status register
must both be unasserted (Green). If not, use the appropriate data block codes to command (0x00) to
clear the flags. Default codes of 0414,3672 to unseal and ffff, ffff for full access can be typed into I2C
Write Block feature, or into the value field of the control register on the Data Ram screen followed by
Enter. Scanning should be halted during this operation to insure the words are received consecutively.

Thank you.
but I don't understand this part " Default codes of 0414,3672 to unseal and ffff, ffff for full access can be typed into I2C Write Block feature, or into the value field of the control register on the Data Ram screen followed by Enter" .

Could you tell me more detail?

You have to enter the codes byte swapped.