Alright. Well I'm not trying to be rude, but I'm going to be blunt. Fifteen minutes of google searching will tell you the MOST IMPORTANT PIECE OF EQUIPMENT you can have is a THERMOSTAT.
Without one you're risking dangerous heat spikes that can lead to horrible burns, neurological problems and even death.
Every decent care sheet mentions a thermostat.
Anybody telling you to feed a pinkie mouse to a ball python is clueless and you should learn elsewhere. But, just like a thermostat, appropriately sized prey is something you research BEFORE bringing an animal home. That only takes a few minutes of googling as well. Fuzzies are also WAY TOO SMALL.
Look at the feeding chart I linked...no pinkies or fuzzies anywhere on it.
As for soaking...maybe he's dehydrated because he HAS NO NUTRITION in him. And rather than just put a band-aid on the problem by soaking, why not actually FIX THE PROBLEM???
And yes, offering food too often DOES stress the animal and lead to further refusals. I've had thousands of feedings with over a dozen snakes over about 15 years. I, and any other experienced keeper, will tell you that you should only be offering every 5 days at least. You even said yourself the minimum is three days, yet though u were offering after two. So you're even breaking your own rules that are wrong.... But yeah...
Your snake is trying to eat anything it can to survive. But you're feeding it basically a sip of water. That'd be like us surviving on a glass of water a day.
So maybe reconsider your sources, they're clearly not reputable sources.