Hi friends
Thank you for your asking. Kindly provide the information below so that we can better assist you.
1. Does the issue appear after any system/apps' download or update?
And your current firmware version
Settings>System>About Phone>Build Number
2. If the "Fingerprint" is turn off, does the situation remain the same?
Settings>Security>Fingerprint
3. Enter "Safe Mode" and leave a 80%-100% phone in sleep(idle) mode in a night.
# How to enter and exit "Safe Mode"
https://www.asus.com/support/FAQ/1005163/If the battery works well in "Safe Mode", please check on any disturbance from the installed 3rd party Apps.
4. If the issue remains the same in "Safe Mode", please try "the Factory Reset"
Settings>System>Reset options>Factory data reset
Please note that once the Factory Reset is completed, all data, apps, settings and personal information will be deleted.
5. Is there any zone heating up while using/idling? How long has the battery been used?
For further information, please refer to the links
[ZenFone/Pad] Power saving skills | Official Support | ASUS Global[Phone/Pad] Tips for battery charging and storage | Official Support | ASUS Global