Can't Boot Images, Am I Stupid?

[HrVanker]

I've been trying to write the boot images to an SD card, but to no avail. I've tried different cards (SanDisk, Samsung), different readers (USB, 2x SD adapters), different programs, etc.

Every time I finish writing the image, Windows sees the card as a 3.9MB drive... Which struck me as odd, because typically when I write a linux image, Windows sees the drive as unreadable and prompts me to format it. When I attempt to boot the card on my Opi5P, I just get the blinking green LED, no fan activity, frozen network lights.

I see mentions of UBoot in some of the documentation for this project... But the instructions on the main/ReadMe page don't mention UBoot at all, and the UBoot instructions in the Wiki section seem to be for specific use cases.

What I've tried:
I have verified that I'm downloading the correct image Opi5P.
Different card readers
Different cards
RPi Imager, Balena Etcher, USBImager
Tried writing XZ file directly, tried extracting and writing the IMG (tried this after seeing it suggested here)