Is this a simple quadcopter, but new electronics?
Many different multicopter designs can be handled without firmware change, just by manually configuring the mixer. If you can calculate a mixer so that you have 4
independent controls, (roll, pitch, yaw, thrust), then generally no code changes are required. By independent, I mean that when you give for example roll, you don't get anything else. If you do get something else, you simply adjust the mixer so that it automatically removes that. You can actually fly a pentacopter (and utilize full lifting thrust on all motors) by tilting (fixed tilt) the motors and correctly configuring a mixer.
Then there are vehicle designs such as tilt motor hexacopter that allows forward flight with zero bank angle where you actually want to add a forward control so you now have 5 independent controls.
Or flying cube with 3 or 6 motors but you want thrust handled automatically so it can automatically hover while flipping around.
Or vision processing for accuracy in GPS denied environments.
I think you will have better luck finding people who will help you, but don't want another job.
Are you trying to keep your design fairly secret for now? If not, open a discussion thread about the design and what you want to do with it. If it is something that requires an NDA just to learn what you want to do, then you will probably have fewer responses. Maybe zero responses.
