After reassembling does the system work at all? If it does what does diagnostics tell you?
It’s going to be a while before the schematics and board-view drawings leak out of Apple or someone reverse engineers things.
I’m surprised you needed to clean the board, did you have a liquid spill? If not where was this system that got so dusty? For such a new system there really is no need to go this far. At best a can of can’d air to blow the fan blades and surfaces is about all you should need here and after a good hard year of service. I would focus on making sure the work area is clean and not sitting on any fluffy cloth like a bed spread and keep the 🐈⬛ off!