Looks like something is occupying i2cbus - I bet, that bq27x00_battery module is loaded at startup. check your blacklist and enforced modules list (refer to kernel-power thread, it was discussed there, "somewhere" - I don't remember locations now, sadly ).

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For quick confirm/deny, try (as root) modprobe -r bq27x00_battery - if it accepts command without errors, and then, bnf starts to work, you can be sure it is it.