The hard reset button manually disrupts the power connection with the battery on the power meter housing. The zero offset will not be affected by a hard reset.
To perform a hard reset on the Gen 3. Stages indoor power meter (971-0103): Push the hard reset button, located at the end of the power meter housing. Upon hard reset, the power meter will reboot and resume broadcast, and the LED indicator will blink for 10-15 seconds.
Note: If you have a Gen. 1 / Gen. 2 Stages indoor power meter, 971-0100 / 971-0101, it will not have a hard reset button.
Please see the related article: How to hard reset a Stages Gen. 1/Gen. 2 power meter (971-0100 & 971-0101).