Gremsy S1 V2 uses its own firmware and is different from Gremsy S1. Please double check your S1 version by looking at the Roll axis.
What's new in firmware version 6.0.5?
Lightbridge 2 dual operator :
+ C1 on/off motor.
+ C2 change mode.
In case you forget how to send the new firmware to your gimbal, please refer to this link: How to upgrade/downgrade Gremsy Gimbal Firmware?