You can pick it up passively over time, and with your skills, if you were to actively engage then I suspect pick up the necessary very quickly, and the rest comes from experience.

I picked up Linux at 13, fortuitously just in time for the release of the Nokia 770 (later getting, and still owning the N900 too).

At that time, getting real dirty with the kernel, hardware, cross compiling etc was necessary, so 1) there were more resources 2) it was seen as mundane, busy work rather than mystical and difficult.

If I were to say how to learn the same things today, I’d probably say Gentoo is ideal - it’s insanely flexible in tinkering, has good resources on compiling the kernel and packages, and I’m a fan of crossdev for cross compiling.

Getting real dirty with hardware and electronics, the obvious answer would be one of the Raspberry Pi lineup, but if you’re very tenacious, patient and a touch unhinged, then I would actually say now’s the time to get in on RISC-V.

It’s still early days, so there’s lots of resources that have very thin abstractions between hardware <-> tooling <-> code. Devices are cheap and exciting. You’ll be on the same footing as most other people so you won’t feel like a dunce.

The cons are that a lot of RISC-V devices get shipped out with very little documentation (and sometimes only in Chinese), binary blobs making mainstream kernels difficult, and you’re learning at the same time, so you might feel you’re ice skating uphill.

Wrt to the bootloader and partition corruption; towards the twilight years of the life of the N900, when it became clear N900 had been abandoned and the N950 was still only available to select few, a bunch of smart people on the Maemo forums started reversing and writing open drivers (uboot bootloader, wifi, camera iirc), so they became pretty documented.

I read about lithium-ion and LiFePO batteries on Adafruit a few years ago, and saw similar projects elsewhere. The bootloader stuff is on Maemo wiki, along with tools to flash the device (which is also a bit of dark magic arts to me).

TBH, I didn't / don't exactly have a path. I started with Raspberry Pi (and Linux for the second time) 10+ years ago, which led me to Arduino, which led me to low-voltage electronics in general. At the same time, I had an unreasonable dislike of google, which led me to flashing LineageOS on a test phone, which then became my main phone, which eventually led to PinePhone, which didn't work out, but was fun.

I don't think true mastery exists in a continuously-evolving field like tech, it's all people just figuring things out, and accumulating enough knowledge/experience means the things you build no longer blow up and mostly do what you want them to ("mostly" being load-bearing here - even the big boys publish errata notices for their chips because even they miss things sometimes).

I don't have a degree in low voltage electrical engineering, but haven worked close to people who are this does all look like grunt work in that field. So maybe get a bachelor in low voltage electrical engineering? It's all as much digital/computational as it is actually physical these days. Lots of educated electrical engineers end up as software devs, often doing the low level coding. Bootloaders, firmware, and drivers are stuff you have to figure out if you want to get modern electrical hardware to do anything.

Can't claim to know the specifics, but there's some supporting links for both the battery and bootloader stuff in the article. The supercapacitor (can be a regular cap too, but would be physically much larger) is for buffering the power supply to prevent the device from shutting off if there's a momentary draw that causes the voltage to drop.

Like everything else,work on the observability first.

Can you grab the current boot partition? Once you have it can you decode it? Do you have a reference boot partition? Can you extract the bootloader from the boot partition? Can you read those binary files? Maybe turn them into readable assembly?

Can you clip a multimeter onto a PC trace? Can you do the same with a scope? Can you decipher what the 'scope capture means? Maybe use a bus pirate instead?

It's all about observability.

Honestly, It is just a matter of starting somewhere. Anywhere. All these hobbies are a huge rabbit hole that seem to converge.

I have friends who started with porting Sailfish OS to their old Android phone and now they are designing their own PCBs for their home automation system. They custom built their own RC cars, 3D printed their own ergonomic keyboards, designed their holiday decorative lights etc..

I have seen a lot of people in my local FPV Drone Racing community, who started with building their own custom drone and then moved on to 3D printing their modifications, tweaking their firmware, building their custom lithium battery packs, designing their ergonomic keyboards, and now fiddling with their home automation software/hardware.

Also installing Arch Linux onto some random piece of hardware, regularly following Hackaday like blogs seems to help.. lol.

A lot of this looks like black magic from the outside because the learning path is mostly invisible