2010 C300 4matic suddenly won't start.

So last week I took my son's 2010 C300 4matic sport down to the store and when I came back out it would not start again. Started up just fine 1st thing when I left so I didn't think anything of it 🤷‍♂️

So at the parking lot I checked battery voltage. It was good. I even tried to swap in another battery just in case the OEM battery was dead but reading good. Nothing. The key is communicating as I do get dash lights and everything I should. Tried starting in N instead of P still nothing. Also attempted to take out the starter relay and jump the 2 connections to bypass the immobilizer and still nothing (but I just had some wire so unsure if I made the connection... So I had the vehicle towed home.

At home I made a jumper to try to force it to start and heard a click but no starter engagement so at this point I figured it was just a bad starter on a vehicle of this age... So a few days later I now have a new starter installed and went ahead and bought a new starter relay as well. Charged battery while I was installing parts. AND STILL NOTHING 😪

So I checked the Check Engine codes it is throwing (had a couple Evap codes that were there before I just hadn't had time yet to replace purge valve solenoid thing. That wouldn't cause no start issue though). These were P2422, P0442, P0496, P0456...

But NOW I have P0607 (control module issue), and P2571 (Direct Ozone Reduction Temp Sensor) codes coming up??? These are both things that can cause the no start condition, but what caused them? Also now the cooling fan is running intermittently while vehicle completely off. It will stop if I press unlock or open door or do other things. But it comes back on a few moments later. I had to unhook battery.

There was some snow a week before this... I've seen some people talking about moisture in the ECM, but with its location on top of the engine and being sealed is that really a thing?? Or could it just be the Ozone Reduction Temp Sensor thing went bad and has caused the car to go into non start mode? And the radiator fan to run uncontrollably?

Or could it possibly just be the key??? 🤦‍♂️ I'm lost here sadly... Hopefully someone read all of this I'm sorry for the length. Any insight would be amazing.