The top right fet is one of four parallell fets for the antispark circuit. The four ones that surrounds the red batt+.
Your problem is somewhere else
Damn. I unplugged the halls and it works again spins normal both wheels. I ordered another Unity anyways off massivestator a bit ago. Just to have here. Idk what im looking at wirh these very much. My friend Dons like thats a blah blah component yada digikey bubba fet something. 
. Thats All I hear. Mosfet. I know what those are. I can make one on kicad. But dk what im making. Did photoshop and illustrator for 25 yrs now. Looks the same to me. Just circuit board pieces instead of brushes. Idk. Learning. Got decks got drive trains learned composites amd suck at it!!! Hahahaha. Alan Chaus the Man!!! Haha. I gotta learn the speed control just because!!!. Inhave to make one. And not a practice one. A badass one!!!. Hahaha. Even if Its only one!. Like learning a song on a guitar that’s really challenging. Or the newest rubiks cube. The speed controls got me hooked. Its something I dont know. And i want the knowledge like gollum from loard of the rings. Hahaha