https://www.amazon.com/Theoretical-Minimum-Start-Doing-Physi...
It's a cool book... written to be relatively accessible, but is actually grounded in the real principles and math used in physics. As somebody who considers himself an autodidact of sorts (in that I'm as much self-taught as formally educated), but who has some awareness of "what I don't know" (and therefore doesn't sit around coming up with crackpot theories about quantum mechanics and what-not), I love this kind of stuff.
One of the authors is Leonard Susskind who is pretty credible. This is a book that is serious, but succinct (as you might guess from the title). Note that there is also a companion volume that is specifically about Quantum Mechanics. https://www.amazon.com/Quantum-Mechanics-Theoretical-Leonard...
All of that said, I do think it's important to note (as others already have) that "autodidact != crank". Plenty of autodidacts are just people who study physics (or whatever) because they find it interesting, but they are aware of their limitations and don't pretend to have amazing new insights that have escaped physics for decades, etc. Likewise I'm pretty sure you can find cranks who have a formal education as well.
