Please follow the below steps for troubleshooting :
1.Tap and hold the power button to power off your device and reboot.
2.Re-activate the feature [Show battery percentage] from setting：Enter Settings > Battery > Enable Battery Percentage
3.Update firmware to the latest version：Enter Settings > About > System update > Check Update
4.Enter Safe Mode: Long press the power button > Tap and hold the option Power Off > Tap OK. If your device works normally under the Safe Mode but turns to be malfunctional after you restart, such error case may be caused by 3rd party applicaitons.
We suggest you backup all the data stored in device and conduct system factory reset
5.Backup your data and perform factory data reset
Note：Once RESET has been executed and performed, all the data, apps, settings and personal information will be deleted after initialization.
If the above steps can't solve your issue, please contact your local ASUS Customer Center for technical support.