My ROCK5B was ordered as a 'blue one' on Aliexpress a year ago; I got a 'green one' and as with included case the price was > 150 euro, it got stuck at customs for quite some time. It was with blank/empty SPI flash and endless boot-loop. That was already known by me, so I had fixed 12V soldered to a male USB-C connector. Same story for ROCK3A, although that one booted most of the time but then while running al sorts of strange errors and or crashes. So I think you have to assume USB-C PD negotiation is not working with the Armbian images you tested. Only the U-Boot starting at sector 64 does matter, rest (Linux) is don't care. If a stable U-Boot or UEFIv1.1 form SPI-flash or SD-card, you have already a very extensive commandline interface or text menu's in the EDK2. But lock up might simply happen because the PSU does not do 65W, instead max 15 W (only up to 3A) and the 5V might drop way too low, just very short dip that is not measurable without good oscilloscope or so. The Radxa image might have a bootloader variant that does do USB-C PD, although I haven't seen proof anywhere that it correctly handles and does operate the FUSB302, but that might simply be because my ROCK3A and ROCK5B came out of the box with empty SPI and for ROCK5B I have ignored Radxa images anyway after the big troubles with ROCK3A, so do not really know what happens with those. So I have no other advice then use fixed higher voltage, formally it is >= 9V according to Radxa wiki/docs AFAIR, but I remember the powertree design actually better than those quick facts and my conclusion was : forget about 5V, use 12V and it was easy decision for me as I use 12V UPS and 3.5inch HDD that also needs 12V anyway.

Armbian 26.2.1 Noble XFCE (BSP Kernel: 6.1.115) + PanVk - 26.2.0~git2605212123.7b286abe336 (https://launchpad.net/~ernstp/+archive/ubuntu/mesaaco) + Box64 arm64 v0.4.3 42ae8b818 (https://ryanfortner.github.io/box64-debs/) + wine-proton-11.0-beta1-amd64-wow64 (https://github.com/Kron4ek/Wine-Builds/releases/download/proton-11.0-beta1/wine-proton-11.0-beta1-amd64-wow64.tar.xz) + DXVK-stripped v2.7.1 ~40fps@720p Grand Theft Auto IV - The Complete Edition

Armbian 26.2.1 Noble XFCE (BSP Kernel: 6.1.115) + PanVk - 26.2.0~git2605212123.7b286abe336 (https://launchpad.net/~ernstp/+archive/ubuntu/mesaaco) + Box64 arm64 v0.4.3 42ae8b818 (https://ryanfortner.github.io/box64-debs/) + wine-proton-11.0-beta1-amd64-wow64 (https://github.com/Kron4ek/Wine-Builds/releases/download/proton-11.0-beta1/wine-proton-11.0-beta1-amd64-wow64.tar.xz) + DXVK-stripped v1.7.3 30~60fps@1536x864 Batman: Arkham City GOTY Edition

Yes, the next step should be u-boot normally. @meco any clue?

Armbian 26.2.1 Noble XFCE (BSP Kernel: 6.1.115) + PanVk - 26.2.0~git2605212123.7b286abe336 (https://launchpad.net/~ernstp/+archive/ubuntu/mesaaco) + Box64 arm64 v0.4.3 42ae8b818 (https://ryanfortner.github.io/box64-debs/) + wine-proton-11.0-beta1-amd64-wow64 (https://github.com/Kron4ek/Wine-Builds/releases/download/proton-11.0-beta1/wine-proton-11.0-beta1-amd64-wow64.tar.xz) + DXVK-stripped v2.7.1 40~60fps@1536x864 Far Cry 2 GamerProfile.xml