Cannot add instinct solar device to garmin connect

My device stopped pairing with my android phone so I deleted it and tried to add it again.

Tried on two different phones but can't get past that the operation failed. Please retry.

I deleted the device from my phones Bluetooth, put it in pairing mode, still telling me to retry.

Occasionally I will get a six figure code on the watch and the phone tells me to look in app notifications for it. But nothing in notifications comes up, also nowhere to type in the code.

Very quickly after this happens I get the fail, retry message again.

My phone's status is always "waiting" , never on.

Pair mode just goes round and round telling me to download the app.

Tearing my hair out.

Wondering if there is a solution or even better, a cable between android phone and device.

Is it possible that the Bluetooth transmitter is gunged up or something. If so where is it located and how would I go about cleaning it?

Any advice grateful received.