Hi
MadaThank you for your asking. One of the common reasons of heating up after the system update is the compatibility between the firmware version and the apps version. Kindly provide the information below so that we can better assist you.
1. Your current firmware version
Settings>System>About Phone>Software information
2. Please try to enter "Safe Mode". If the function works well in Safe Mode yet the issue remains out of Safe Mode, please check on any disturbance from the installed 3rd party apps.
# How to enter and exit "Safe Mode"
https://www.asus.com/support/FAQ/1005163/3. Also, please try "the Factory Reset", then install the apps back one by one under observation. To check if the issue appear right after any apps' download or update.
Settings>System>Reset options>Erase all data(factory reset)
Please note that once the Factory Reset is completed, all data, apps, settings and personal information will be deleted.