Any processor system can suddenly "reset" by static, even if there is a watchdog incorporated. It all boils down to the contents of memory (that is not used by the program running), so by pure luck, a "runaway" CPU can easily go "directly" to reset instead of the WD firing, a lot of chaos is going into this equation!
Isn't it correct that the ECU's with the "#" after the version number identifies the ECU as a "fast" reset type, if a "powerfail" occurs, the engine will be kept running after such a reset situation ?

I have had 1 shutdown because of the "PwrFail" message, this was in a baby boomerang with a P60SE, 4 minutes into the flight. I touched nothing in the plane, and it has since flown 100's of flights (and maybe 50 before it happended), never seen it before (or after) this single incident.
In my honest opinion, I think that there was/is some software bugs inside the ECU, JetCat had in a litlle over a year made many releases of their firmware (which is on one hand good, as it shows that "something" is being done, on the other hand bad, as it shows that something is/was wrong )
Anyway, I have fairly large number of JetCat's here, and I have never seen any problems with them than this single "PwrFail"