For any product with microcontrollers, you might be able to locate JTAG connections and use that to debug some of the functionality. But that area requires even greater amount of knowledge and experience.

There are a lot of good videos on Youtube, for one. Louis Rossmann has some good stuff (especially his older stuff), Dave Jones has some good repair videos (intermingled with a LOT of other stuff, though), and there are plenty of other channels dedicated to electronics repairs.

Having said that... you'll need to know at least a bit about electronics (qua electronics) before going terribly far with electronics repair. Much the same way that one could only get so far at debugging and fixing code, if one didn't know something about writing code in the first place.

So... there are, again, videos on Youtube. The Vocademy channel, for one, is a great resource for general electronics theory.

And books. Don't forget books.

I'd suggest, depending on your existing knowledge level, find a couple of books on basic electronics, load up some of those videos, get some components and perfboard and a soldering iron and some basic test equipment (a multimeter and an oscilloscope are a good start) and start building simple circuits. And gradually expand the range of circuits you build to become more complex over time. More or less simultaneously, start watching YT videos on "electronics repair". The thing is, there's a difference between knowing "the theory of electronics" and having the debugging / troubleshooting skills, intuition, judgment, etc. to diagnose faults. The two things are related, but are somewhat orthogonal.

At some point, find used junk non-working electronics, either stuff friends/family will give you, or stuff you dig out of a dumpster, or buy at thrift shops, or buy off of Ebay listed as "not working / for parts only" and start trying to fix things.

So basically... "learn theory / build stuff / fix stuff" in an iterative loop. That's about the best advice I can give.

I reckon it will be valuable in the future that comes.

I agree. That's one reason (not the only reason mind you, but one) that I've spent a modest amount of money over the last year or two, upgrading my electronics lab, in terms of tools, test equipment, etc. I mean, I do this stuff for a hobby, and it's been a nearly life-long thing for me anyway. But more and more recently, I find myself thinking that the ability to repair/hack/build electronic "stuff" will be a skill with serious value. I just wish I had more time to commit to it.

One upside to this approach is that as you improve it can pay for itself by reselling the fixed items.

I've learned not to fear B+, but to give very healthy respect to anything more than 500 volts. (Only use 1 hand, keep the other behind you, always have a safety partner, etc)

I've learned to hate Silver Mica capacitors. I've learned how to track down the bad ones that cause the "crashing" sound in old radios.

I've learned that in very old electronics, you can let smoke out, and things will still work. I've gotten good at seeing where the smoke comes from.

You'll definitely need to learn to solder. I'd suggest starting with something like an Arduino starter kit to get a sense of how components actually interact.

But remember, if something is dead, you can't really make it worse. (Just be careful not to make yourself worse along the way)

2.Soldering iron, for starting out I suggest spending a little more and getting a Hakko 888 instead of something cheaper.

3. Flux, Leaded solder, Braid.

4. Broken things you want to repair (for me it has been electronic musical instruments).

5. Practice, Patience, and hobby money.

6. Pay for Youtube Premium.

7. Ali Express Account.