OnePlus 3T User's Manual

To improve battery life on the OnePlus 3T, reduce screen brightness, disable background apps, enable battery saver mode, and update to the latest software version.
Check the charging cable and adapter for damage, clean the charging port, try a different outlet, and restart the device. If the issue persists, consider contacting support.
Go to Settings > Backup & Reset > Factory data reset. Follow the on-screen instructions to complete the process. Ensure you back up your data before proceeding.
Press and hold the Power and Volume Down buttons simultaneously until you hear a shutter sound or see a visual confirmation.
Clear the cache, uninstall unused apps, update the software, and restart the phone to enhance performance.
Go to Settings > System > System updates. Tap on 'Check for updates' and follow the instructions to install any available updates.
Use the OnePlus Switch app to seamlessly transfer contacts, messages, photos, and apps from your old device to the OnePlus 3T.
Enable Developer Options, turn on OEM unlocking, then boot into fastboot mode and use the command `fastboot oem unlock` on your computer.
Restart your device, toggle Airplane mode on and off, forget and reconnect to networks, and reset network settings if necessary.
Clean the camera lens, restart the camera app, update the app, and reboot your device. If problems persist, consider a factory reset or contact support.