iPhone 8 Won't Turn On, No screen, Very hot

Hello!

My iPhone 8 has stopped working after I charged it, the screen was black and the phone was very hot, I tried ‘hard reset’ and charge it after my battery was drained. However, it didn’t work at all (not getting even warm from charging). I ordered a new battery and a board to charge the battery. The old battery was dead, I couldn’t charge it even with the board. The phone still didn’t boot up with the new battery, the screen was black, the board got hot in the upper part

Here are my phone’s measurements https://ibb.co/0cmjNhf

Actual photos of the board. https://ibb.co/ThBmkdn

https://ibb.co/TkShJ3f

Thanks in advance for any help!

Edit: Found out that u3100 is getting very hot.