Since the server pushes update notice to different serial numbers by batches, it may take some days for you to receive the FOTA notice. Thanks for your patience. You may tap “System updates” in [Settings] >[System] to check if there is new firmware available. Or, you can also try to manually update firmware by referring to the following link. How to update firmware on my phone?
【Release Note】 Updated 2019 Sep. security patch level. (20190901) Improved speaker quality. Fixed screen flickers at low brightness. Optimized the system stability.