Am I doing something wrong/missing something?

[fireflii]

Firstly, a rat pup is going to be a bit too big for a 69g ball python. I like to switch mine to rats as soon as possible, but if you're having issues, it might be best to stick to what the breeder did and figure out if its your husbandry first (although based on what you've said, it sounds okay). It wouldn't hurt to bump the ambient temperature up a little bit to low 80s (not that you necessarily have to). 75F is okay, but you don't want it to fall below that for long periods of time. You also want the hot spot at 90F, and you need to check it with a temperature gun (whereas the ambient you'll need a digital thermometer if you don't have one; analogs are very inaccurate). What's your humidity? It should be about 55-65% (or 65%+ if he's in shed).

When you say he's active, what do you mean? Is he surfing the side of the tub constantly? If so, something could be off with your husbandry (temp, humidity, etc.). You can also cover the sides with something like dark pieces of paper, if your tub is transparent, so it gives him a sense of safety. Adding in decor like leafy vines is also good to help give some cover. A picture of your enclosure would be helpful. But it sounds like the mouse might have scared him off of eating. Also be sure not to try feeding too soon between feedings (try every 5-7 days, not every 2-3 for example). Try not to interact or handle him while he's off feed for now, too, unless it's to clean the tub.

Otherwise, I would--personally--try a f/t mouse hopper. Just in case if it helps, what I do is put it from the freezer to the refrigerator the morning of feeding day (since I feed at night). When you're ready to feed, put a cup of water in the microwave for about 40-50sec (hot but not boiling). Put the mouse in a plastic bag (like a sandwich bag), then submerge it in the water for about 20min. What I found with mine personally was that he didn't want to take f/t because it didn't smell like food. So, if you can, get some recently used rat or mice bedding and put it in the bag WITH the mouse when you heat it up. After the minutes are up, hit it with a blow dryer for just a few seconds on low (live rats/mice have a body temperature of about 100F), then when you feed it, wiggle it a bit so it looks like it's alive. That's what gets mine to eat.

Obviously there are other methods, but I find that works best for switching to f/t (assuming your husbandry is correct).

Summary: Might not be eating because he got scared, but double check your husbandry: ~90F hot spot, ~80F ambient, ~60% humidity, dark + crowded enclosure. Try f/t mice hoppers or rat fuzzy, not rat pup, and try every ~6 days.