iOS downgrade

Dear all

I had face Id and battery drain problem after installing ios 13.4.1 and I am still having the same after installing the latest update i.e 13.5 ... even I have done all kinds of suggestions suggested by apple community . The ambient temperature of my area is 35 to 37 degree Celsius.

even I restarted my iPhone after allowing sufficient time for self cooling .

my iPhone simply got heated up as soon as I restart my iPhone. And then onwards my Face ID is stop working and battery also got drained very fastly.

moreover I am trying to set alternate face id but my iPhone informing the following “ Face ID is not available. You can setup Face ID later when I phone cools down”

I approached authorised iPhone service centre, they format my iPhone and installed iOS 13.5 and they told me to use the iPhone for 2 days with charging, it will automatically solve my problem. But it not happened so....

My purchase date of iPhone is 4/1/2019 and it's real duel sim model ( China/Hong Kong) purchased from Kuwait....

It is more than 1 lakh rupees phone and I totally disturbed ....

Can anyone help me to come out

Please

I have purchased at eureka shopping center Kuwait on 4/1/2019 , cost was 405 kd