Help With Aggressive Shelter Puppy?
I have a now 9-week-old shelter puppy named Apollo. We got him at 6 weeks old. He is a (primarily) Lacy dog, American Pit Bull, and Husky mix, according to his DNA test. I'm a pretty experienced dog owner, and his constant companion is my 3-year-old Husky mix, who is also a shelter rescue. I mention this only because I trained her, and never had these kinds of issues with her. I'm well aware that puppies bite and dogs have different personalities, so Apollo won't be exactly like his "sister", but this behavior isn't that. Apollo nips and bites like any puppy, but whenever he's frustrated or corrected (we don't use any form of physical force or punishment, just a firm "no"), he aggressively snarls, lunges, and bites hard. He'll do this repeatedly, even if he's told "no".
I know it's frustration-based behavior, and I've tried saying "ouch!" (that excites him more), standing up, tucking my hands away from him, and stonewalling, but nothing so far has worked. Right now, I'm trying to work on "touch" as a method to try redirecting him, but I would appreciate any other possible solutions or insight into the problem.
Edit to Add: I should've mentioned in the post that he's on a very strict schedule, so it isn't that he's tired. He takes 3 enforced naps a day.