Good question....
It all depends on what strength of field, or static discharge, Jim got into.
You'll note, things like sensitive computer boards and most electronic IC's come in a metallic coated plastic bag. This is to prevent static and strong fields from damaging the components even if they are OFF.
A power-plant's job is producing tremendous fields....so on or off, his gps/camera/phone, etc. could have suffered damage.
Manufactures work hard to prevent this but sometimes nothing works.

How far? No telling. He could have had a flakey part in the GPS that just needed a good excuse to go. Enough discharges from scooting across carpet can kill these things.