The Amazfit GTR smartwatch is receiving a new software update that lets you set a timeout on the Always-On Display, 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.