[HOWTO] Installing OPNsense on EOL Velocloud EDGE 510 router

[LGDL]

I recently got three Velocloud EDGE 510 routers and installed OPNSense following the information from this previous post:

https://old.reddit.com/r/opnsense/comments/1mv3how/repurpose_velocloud_edge_510_router_wopnsense/

A few things changed and I was blocked at two spots, for some reason the default root password didn't work for me, etc. So I documented everything in detail including what didn't work for me, I hope it's useful and it encourages more people to try OPNsense with real hardware.

BTW if anyone knows where to start looking to have the ability to change the LED color, I'dlove to use that for some notifications, including after boot (I miss the sound other hardware do at boot) !