If the LabQuest 2 update fails to reprogram the fuel gauge successfully, apply the update again. For most units, a second update will reprogram the fuel gauge as expected. This error is likely caused by the state of the fuel gauge when the update is applied and will definitely happen if the unit is not under AC power when the fuel gauge reprogramming is happening.
If the second update fails, reboot the LabQuest (Home > System > Reboot), then apply the update one last time. If you continue to have problems reprogramming the fuel gauge, contact us at email@example.com.