What he said after 2:31:19 (in Italian) was interesting, but I think he simply toggled the main switch of the power supply.
Pictures from http://www.sifferkoll.se/siffe…emo-in-stockholm-cop-550/
Yes that would be interesting. I tried to listen with 150% volume with headphones, but still could not not hear his words properly.
I played again with 0.5xspeed setting and all I could pick was: 2:31:05 Rossi could say something like "Whi... I have to soun...." and Fabiani replies in English "The switch" and again "...switch" when his hand reaches the switch. Maybe native English or Italian speaker with higher volume could pick more. (at 2:31:19 you refer to I think it is Matts voice behind verifying calcuations 'Okay,... how much time...")
You are propably right. Anyway before that point Rossi seems to search power switch switch for real (for fraud they would have practiced it carefully). Further looking at Sifferkolls pic you posted, PSU seems to be around there inside the case. So I also guess it was the just because they had shut off the controller while changing setup to avoid damages while removing the reactor from circuitry.