Hi
pjjibinThank you for your reply. Your passed SMMI test indicates that your hardware shall be fine. As you mentioned before, you have performed the Factory Reset already, right? Please try the following steps to access recovery mode for the Factory Reset:
0. Try to back up your data with USB cable
1. Power off the phone, then keep pressing "volume down key"
2. Press "power key" and stop press " power key" once you feel the vibration. Still keep pressing "volume down key".
3. Stop press "volume down key" once you enter [Android Recovery] Screen
4. Choose "Wipe data/factory reset">"Yes"
5. "Reboot system now"
#Hardware Reset Guide
https://www.asus.com/support/FAQ/1006346/Please note that once the steps are completed, all data, apps, settings and personal information will be deleted.
If the issue still persists after performing the Factory Reset in recovery mode, I may need your logs for further checking.