Ring doorbell pro keeps entering setup mode

My brand new ring doorbell pro is doing the exact same thing with re-entering setup mode and going “offline”.
Upon setting up it tells me it’s updating software but a minute or so later I get the dreaded white flash and spinning white lights with announcement that it’s entering setup mode.
I’ve tried everything to get it to update that software correctly, with no luck. It’s driving me mad.
Voltage fine. WiFi hub literally 30cm from doorbell and reading -31db.
Clearly the firmware.
What do I do?