The rocker switch behind the two window switches on the drivers side snaps on to a rod/lug at the top of a little white box with a contact.
When down or on the passenger window will operate either from the passenger switch or the drivers side.
When its up or off it renders only the passenger totaly window inoperable...
Now reading from your description of where your son found the fault, this sounds like the part that was causing the problem.
Regarding the little white box/contact, there is a recess with a spring & a ball bearing (a bit like a tiny version of a catch you get on one of those "old school" cabinets.
This gives the switch it's definitive click, & holds the contact in place, other wise the rocker switch would just rock/flap aimlessly about. (especially if you brushed it whilst operating the windows).
There's also another spring that is housed behind the actual metal contact that pushes it forward to complete the circuit.
It could well be that one of the springs & or the bearing "jumped the housing" making the switch inoperable & stopping your window from working...?
(he says coming up for air!!)
Now, i have a few spare bits (i seem to butcher them for a hobby)

i ended up using a Mazda 626 switch, in my opinion more robust & a lot cheaper..!