RadioMaster TX16S User Manual page 17

Failsafe not set warning: This is a warning that the remote-control fail-safe
protection is not set.
Alarm Off Warning: A similar warning will appear if the sound mode of the
remote-control settings page is set to mute.
SD card warning: If the SD card file version used does not match the remote
controller firmware version, this warning will appear. The figure requires 2.3V0026
version (the SD card content needs to be updated when upgrading the firmware).
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