As a fellow programmer and electronics tinkerer, the book that helped me out the most was Electronics for Dummies. I generally hate the whole "for Dummies" book line, but really did explain many of the things that the other books took for granted and assumed I knew.
"Its where NVIDIA's spy hardware is installed. Quick, smash it with a hammer!"
Joking aside, kid, how old are you? Graphics cards used to be COMPLETELY naked on both sides and you could see circuitry like this all over the card.
This will help you understand the basics of what you're looking at.
https://www.amazon.com/Electronics-Dummies-Cathleen-Shamieh/dp/0470286970
For anything more, invest 15 years of appropriate engineering education and a shitload of money if you're REALLY that curious.
Start with the basics: https://www.amazon.com/Electronics-Dummies-Cathleen-Shamieh/dp/0470286970
I already know all about stacking batteries. . We have been doing it in our gameboys, rc cars, rc helicopters, and many other everyday items. What makes us different? Nothing. The "fear" of stacking came around when regulated mods showed up. Over volt a regulated board and you blow it. Now when you stack two batteries the safe school of thought for people who don't know electrical theory is if you have 2 10 amp batteries stacked or in series. You now have a 10 amp battery. When in reality they share the amperage across each other. So those same two batteries now have a 20 amp capability.
You may want to read this book before you talk about stacking. I did. I also have quite a few friends who have degrees in Electrical Engineering. I can have them link you some other useful reading. Thanks for the concern.
PS: I use Li-Po Batteries in series in RC Helicopters. This is more than a standard practice, but the normal. Thanks for the laugh.