Endrun Tech Sonoma - cannot factory reset: help!

I picked up an Endrun Sonoma D12 to use as a strat 2 in my network (have GPS strat 1’s, just want to lighten the load on them and I like this box / footprint)

Problem is promoter failed to wipe it & it’s still locked down with their settings / security. I cannot factory reset this thing. Factory default UN/PW (root/endrun_1) does not work. “Initjffs” at boot does not work. So I’m at a brick wall.

Anybody know how to reset these fricking things? Any help hugely appreciated!