title_body: Can I salvage a 4in1 ESC? I have a 4in1 Brushless ESC that only one ESC burned out on, but the rest should still be usable. Is there a way to salvage it and use a single ESC to replace the burned one or something? If so, how would I go about doing that?
upvoted_answer: You would have to be careful so as not to lose some functionality like current sensing or affect the CG of your quadcopter.
  
  One way I could see this working is leaving the 4-in-1 ESC on the stack in your quadcopter frame and only wiring up one ESC, with the signal wire from the standalone ESC wired to the pad on the 4-in-1 ESC where the dead channel's signal comes in from the flight controller.
  
  In order to not affect the center of gravity of your quadcopter and destabilize it, you would likely need to mount this extra ESC in the middle of your frame. Normally with either a 4-in-1 or standalone set of ESCs, the symmetry the ESC components on the frame balances out and you wouldn't have to worry about messing with the CG too much. 
  
  You would also have to make sure that the 4-in-1 and standalone ESC operate on the same signaling protocol (Oneshot, Multishot, DShot, etc.), because Betaflight (et. al) expect all ESCs to be capable of the same signaling method.