I may be wrong ............ but I can't ever recall in all the years of BB faulting, receiving any info from the Chief Engineers Office regarding the 'Dying gasp', and/or unplugging the power first before working on the circuit ?.
I'm not saying whatsoever that it does or doesn't play a part, I'm simply surmising as to the impact of unplugging the DSL lead first as opposed to cutting the power, due to us not receiving any guidance from them above ?? They usually inform us rapido-style if something has been found that would seriously affect the circuit ?