What to do if the Xiaomi Watch S3 fails to measure the blood oxygen?

For your reference, here are some troubleshooting methods as below:
1. Check whether the protective film on the back cover has been torn off. If not, please wear the watch again according to the measurement failure prompt to continue measuring blood oxygen;
2. Turn off all-day blood oxygen monitoring, open the watch blood oxygen application, measure blood oxygen once, and check whether the blood oxygen light on the bottom of the watch will light up while the watch is measuring. If it does not light up, you can unbind and rebind or restart the watch;
3. If the measurement still fails, you can apply to the after-sales service center for inspection.
Note:
The back cover of the watch comes with a protective film to prevent damage during transportation. Blood oxygen and heart rate measurement both depend on the sensor on the back cover. When using these functions, you need to tear off the protective film. Otherwise, the sensor light will not be able to contact the wrist skin, resulting in measurement failure or no value.