Earthing the technician was a standard wind up on apprentice courses at Volvo, we could easily get them to put one foot outside the car and ground it ;-).
The point with all electronics and it's the same with airbags is to only touch what you must and not to go wiping components and terminals with fingers. I ran SRS training at Volvo for 12 years, it was a neat course to do (about 6 a year) as we got to deploy airbags which got everyone's attention. Lots of garages did not see the need for explosives safes as required under the handling regulations but they saw the need when I used to place an upturned galvanised dustbin on top of a passenger side module (110 ltr in those days) in the car park and blow it the height of the building, as we did the training for Police and rescue services we got away with stuff ;-).
Airbags and Pyrotechnic seat belt tensioners are not fussy, they will go bang wth any kind of voltage. I totally disagree with the statement about shelf life, at least for early airbags, they used to be packed with deployment medium that resembled small tablets and these had a shelf life and the car (at least Volvo's did) had a sticker on the drivers side B post stating the airbag exchange date. This was conveniently 'forgotten' when SRS became standard and bags multiplied. When I left Volvo some years ago we were up to 8 as a norm and it was a case that a full deployment wrote off the car, not in terms of damage but in replacement costs, the figure at that time with replacement trim ((and often a new steering wheel and column) averaged £1K per bag!
