Permanently stuck in "registering with a cell"

Bringing an imp006 eval board back online. It was operational, then we moved to a new IMP enabled product, so I shut it down and deleted it from Account Development Devices based on recommendation. Since then, want to use it again. I performed “clear a device settings”, then used “configure a device”. Got green light during Blinkup, followed by the long/short/short red sequence (registering with a cell) and there it sits. Checked twilio to make sure SIM is active - all good. Not sure what to do. Anyone solve this one?

Hi, I see you’ve also opened a zendesk ticket so have responded there and will summarise here afterwards.