Ok that was fun to read about!
Life at 16 does get more complicated, when the toys are getting larger!

I think we must lost the interpretation of a click happening where and to what a click somewhere else could mean?

We went with the click as being under the dash but was there anything else going on?

Does the engine crank over but does not start each time?

Is there absolutely no cranking and only a faint click to the right under the Dash and then it cranks?

When she or you do this operation, does it seems to me to VARYING the symptoms any or just number of times it clicks in succession?
Without a good follow up of descriptions or collaboration of what is expected to happen, It is the HOLE in the donut picture on both ends of the post.

She just needs to learn to break down the sequence, for all of us, but that's going to require some teaching about the cars inner workings.
Sorry for ya bub! Drivers Education, chapter two!

I like the bad cables idea as well. Voltage drop can be a real killer in, down stream, things causing intermittency! High resistance, anywhere, is an electrical gremlin!

My thoughts are also going with a faulty ignition switch, that's replaceable from the back side, by removing to screws.

The reason I like the switch idea is because its touched by human hands. Things handled wear or get beat up by abuse a lot.
I could tell you a story about "A" driver side door lock on a relatives car! Amazing how fast people can STAB into those things over and over and then, wonder why they have to wiggle it!

These switches are very reliable but at the ages of these cars, it maybe about the right time.
Those contacts have to seperate functions even though it seems like a seamless motion!

In other words, maybe the circuits contacts are breaking up during the transitions dropping ICU or ECU power supply and therefore the relay goes bonkers!

How old is the CPS? They get flaky in half the time and it's between the switch and the computers.

Just my guess like I always do! But hey, I'm far cheaper than the man in blue with those flashy arm patches! :-)

Phil