Just so everybody knows, the responses here are more helpful than the those of support, even when the issue is classified as high priority.
I received a response at 22:30 my time, to which I responded, along with stating that I was available to work on the problem for a further 90 minutes (that would be 00:30 local time) and I have still received zilch - nothing.
An RMA should have been issued last night and a replacement device dispatched before COB. It doesn't matter whether it was shipped from CA or UK, it would be here by now.
And how much of a snowflake is the MX64, that it fails, permanently when uplinking to a different device?
What am I supposed to think?