If the issue persists like this, it should be taken to a service center and that is where it will be repaired, if there's indeed a problem on the hardware and not through Lazada.
Just one suggestion, have you tried having the phone off for 1-2 hrs? If you want to try, might as well drain the battery.
Using any apps or playing games while other functions are on like data/wifi/gps can really increase the thermal state of the device. If you want to try more, put the device on airplane mode, set the brightness to the lowest and kill any running apps, since you just reset the phone, keep the default ones only and uninstall those that you can uninstall. Better to do it around 20% or lower and turn the battery saver auto to off.