…took my 5” basher out for a “maiden” with a new profile… was flying fine.. I got cocky and put it into a tree. Tried turtle mode-ing, and it just stopped responding .. except the beeper.. oh, that was working JUST fine. I retrieved it, noticed a lost some props and one motor seemed “stuck”.. got it loose, powered it up, armed, lost that motor.. so I thought.
I installed another (older) motor, plugged in betaflight, powered it up GOT TONES.. and the motor I just installed smoked! Since I did a quick / fast solder job and their proximity to the frame.. I thought it shorted to the carbon fiber. Then I remember I have had motors shorted by screws and never had them smoke like this, thought it may have been the motor…
Removed the motor, added BF, battery( no tones) and no smoke, no issues .. except for the missing motor..
So installed another (older) motor ..added BF, then lipo, tones and SMOKE…
I’m guessing a smoke stopper would have caught this .. but it never occurred to me since I was just swapping motors…
Anyone else have a esc “fail” like this? I’ve only seen them fail “dead”

It is possible for damaged FETS to be stuck in an on state (ie shorted) and sounds like that is what happened in your case. And I believe a smoke stopper would have saved your from toasting your replacement motor as it would have cut the power very quickly.
For micro bench testing, I have the habit of using a smoke stopper when testing motors, but for a 5" that might be different as the higher current draw motors might trip it more often even if there are no issues.