Wow!

What a harrowing experience for the poor little guy! When you first thought you pulled the turtle out from the pump intake, it was night time right? So most likely it was something else that you pulled out and not the turtle. I don't think it would have been able to survive something like that if it felt and looked like its guts had been sucked out.
When you found him in the bottom of the ponds was there any mud or decaying leaf litter down there? Or something else wet or cool that he was able to shelter in? That's pretty hard to imagine that a baby RES could survive for 4 weeks in that kind of heat without any water or shade.
Well, either way, glad to hear that you have a healthy baby turtle again (actually 3 now).

Welcome to the forum too!