The Amazfit GTR smartwatch is receiving a new software update that lets you turn on/off the Always-On Display at a specific time, which should help conserve battery.
Additionally, the new firmware, sporting version number V188.8.131.52, fixes the black screen problem and extends the alarm ring time to 30 seconds. Besides, it brings a reminder that will pop-up when the AGPS expires.
This update is currently seeding in Malaysia and should expand to other regions soon. You can download it by heading to the Settings > Check for update menu in the Amazfit app.