While the version is correct that fact that it was set to DCHP says that yes it has been changed from the factory static IP setting. OpenWRT is the gui that comes up because it is the 'Advanced' one you can switch to from the default Avalon one. Yes, by default the miners are pre-configured to point at Kano and should be using Canaan's standard worker name.
That said - as you rightly suspect/fear who knows if anything else has been changed or added.
Definitely would reflash the SC card with Canaan's official image!
Assuming you have a SD/microSD reader/writer follow
Canaan's RasPi Imaging instructions.