So yesterday it was kind of warm out, and my brothers 5th gen didn't start around 3 o clock. He said he turned the key and heard no clicking, but the dash lights did come on.

Then around like 6 my mom tries, and it starts up. What the heck is going on?

 

So did he do any sort of diagnostics, or just give up?

Have you tested the starter?

A third party trying to diagnose what happened to two other people over the course of hours, with not much detail at all, isn't exactly the easiest situation.