My phone get heated by rear power buttong and touch stop working

Hi

When ever i turn on my LG v20 it work fine .

But after using for some time it get heated near by power button on the back and LCD touch stop to work.if i turn off phone and phone get cold and turn on again it start work again.

Some time even after restart doesn't work.

Could you please help in this situation.its not LCD as it do the same with a replacement LCD.i tried two. Lcd on it...one brand new replacement one and one orignal from another phone.it seems. To mee some problem from mother board.

.

Thank you