RTOD on hot days, goes away when car has sat and battery has been reset

Okay, be nice to me as I am a new driver, new car owner.
I recently purchased a 2007 Prius from someone I knew. The car was pretty roughed up, but was said to have the hybrid battery replaced a few years prior to me getting it. It sat for around 2 years before I bought it and drove it. My dad is a mechanic so her tuned it up and it drives great. The only issue I have had at all is the check engine light (o2s, not a huge deal and will be replaced) and the RTOD. I have been reading many posts here and elsewhere about what it could possibly be because it comes on and drives fine still, and goes away again.
I noticed it coming on when I have driven it for a while (40ish minutes or more) in the heat (in Minnesota, so anywhere from 85-100 F) and usually if I'm doing stop and go on city roads or traffic. The triangle goes away after the car has cooled and the battery has been reset. It does not go away if it's just cooled but not reset, but won't come back on if I reset it until I drive it in the extreme heat again. There's no heat warning showing up, and just the red car with the exclamation point on the center console. I got myself a OBD2 diagnostic interface and ran tests with the dr.prius app and no codes came back at all for the battery, but I ran them when the triangle was not on the dash anymore. I replaced the air cabin fan and filter not that long ago as my AC didn't work and now it works great. But the triangle came on the first time I used the AC. I'm just at a lost point currently. I only paid $2000 for the car so I'm not trying to take it into the dealer to get fixed (it's quite a bit roughed up cosmetically as well and I know as a woman the dealership with rip me off big time anyways) the car has 270,000 miles on it but is running fine otherwise. Any ideas on what to do?

 

Worth noting I suppose: when I bought the car my first thing I did was buy a new 12v battery, but the Walmart I got it from didn't have the exact one I needed so my dad advised me to get one that was very similar. He installed it and it's a little bit too big but he made it work somehow with some extra metal pieces (really not exactly sure how, but its too big and doesn't fit correctly, but does work) the battery display on the front is fine, charges up fully even after draining fully. I'll attach the dr.prius screenshot here. As well, the main page on the app did state, after doing the 45mph life expectancy test(which showed about 50%, to be expected on a car with 270,000m) that the battery was hotter than I would want it to be, at about 95-100F. Didn't run weird though

 

Okay, so I used the dr.prius to change the temp the fan will come on to cool the battery and my car didn't give me the RTOD for a while. I have also been cautious of driving it on hot days tho. Today I drove about 20 miles and the red triangle came back, first time since getting the obd2, and I ran it and the code P0a93 came up - Inverter coolant pump. Not sure exactly what this means though. Any ideas on what to do next in terms of figuring out what exactly could be wrong?

 

I looked through a bunch of posts on here about this code and the pump itself and decided to check if the coolant tank was producing "turbulence" and it is not. Still as a rock. I am assuming this probably means that it's the pump, and that I will need to get it replaced. I plan on replacing it myself with my dad, since my car is at 270,000 miles do you think buying an non-OEM part would be okay since it's likely not going to go for another 10 years

 

Wanted to update everyone. It was in fact the inverter coolant pump. Due to finances and immediate need I purchased a $40 part on amazon and placed it on july 12. It fixed the RTOD and I have not had an issue since