Help Install ODROID-HC4

[Joel Carnat]

Hello,

As it was referenced on the arm64 web page, I bought a Hardkernel 
ODROID-HC4 to run OpenBSD. The thing is, I can't boot the OpenBSD 
installer at all.

I have successfully ran an armbian instance from the microSD card so I 
expect the hardware to be fully functional.

I have tried using install71.img and install72.img on a microSD card but 
couldn't boot from it. The hardware comes with Petitboot, not with 
U-boot. I'm not sure whether this matters or not.

Can someone who uses it explain with a bit of details how to install/run 
OpenBSD on this particular hardware?

Thanks a lot,
Joel C.