Got some results on ESC's...
BK controller a little bit complicated to take apart but can be done
TOP view and
Bottom view
Schulze - simple if not waterproof version
Top view and
Bottom view
Mamba Max - easy to take apart and looks like poor design in output stage
Brains Top view,
Brains bottom view,
Fets top view and
Fets bottom view.
Thank to Mike for provided ESC's.
Later next week I will put update on possibility putting two mamba boards in parallel.
As for now, I will put some time into fixing some of them and testing with new driver boards. After conversation with Mike, I decided to proceed with 6S version with 300A capacity.