Hi, what is the name of this part? And where can i find a replacement?

https://ibb.co/eoKtrG

Its for the P3S

Oh yeah, and why is my camera not showing a video in the app? Everything looks fine

Looks like the top cover that covers the wifi module board and connection to gimbal. Is everything plugged in on the bottom?

As I mentioned on your another thread, to ensure the safety and performance, we'd recommend you to send it in for evaluation and get it repaired by engineers. Besides, unauthorized modification will void the warranty, for details, please visit: http://www.dji.com/service/policy