Different threads for the same problem make it very hard to keep track of things. Which BL-Ctrl do you have? V1.2 and V2 are very different.
The MK Bl-Ctrls are a bit of a mystery to me. I only know of two people that may have a clue about the technical aspect and they only post on RCG as far as I know. You will probably find the best answer on the .de site to a more technical problem.
One problem people run into is that a bad motor can fry an ESC phase, and a bad ESC phase can fry a motor. It would not be a bad idea for you to get a couple cheap stock ESCs and motors to do testing. I also made a post here with motor testing links.
I have noticed that a bare motor can spin up properly with only two phases firing. If you put the weight of a prop on it then you can see the stuttering and the bad phase.
I do not think that the MK BL-Ctrl error feedback extends to or past the FETs. IOW, I don't think it can tell you if a motor winding or FET is bad. I could however be very wrong on this. Someone please correct me if I am.
In any case, if just one FET got too hot to touch as in your other video, something is very wrong. It is sucking down way to much power and a regulated power supply with an AMP meter would have told you that - maybe even before real damage happened.