Running electricity through metal magnetises it.
As seen in the aftermath of lightning strikes, metal objects become magnetic. It's also how electromagnets work.
The usb wallet would have been wiped, even if it had somehow remained intact with the current running through it.
Electrical burns are distinctive and not confined to the areas of contact. There should have been some burning where the electricity exited the victim's body.
More importantly, simply put, electricity creates heat. (That's why they're call electrical burns.)
Had the victim touched the live wires at the substation as shown, the result would have been too horrific to show. It would have at the very least burned his hands and face to the bone, and caused burns and charring most of the way along his forearms and down his neck.
Neville's laptop would not have lost power when the power when out. If it was plugged in, it would not have been at dead 0%, since plugging it in automatically begins charging. The Wi-Fi may have been lost, preventing him from editing his typo, but the laptop should remain on.