nRF52840 initial setup issue

I have a XIAO BLE 5.0 nRF52840 SENSE board that I’ve just unpacked and plugged in, but I can’t get it to register.

It’s flashing rgb as soon as I plug it in and no amount of clicking or holding the reset button seems to help get it Into the correct mode. I definitely have the correct boards loaded in studio, so that’s probably not it.

I’ve never had this issue with any of my previous XAIO boards. Any suggestions please?