What sort of failure is this?  

RE:

It is a jam.  Heat creep is only one potential cause.  I would try a different filament first.  

Second I would try: 

If this does not help: I would contact support (echat) since your printer is pretty new and they can walk you through some fixes.  

RE: What sort of failure is this?

Hi Chuck, thanks for the advice.

I tried it on three prusa PLA filaments (all kept in sealed containers with drying agent) and all have the same issue.

I have run through the video a couple of times, have done what he suggests.

I've also followed the Knowledgebase extruder cleaning and cold pull pages.

So I'm all ready to try a print again, but I must have done something during the above processes as when I tried to to do the bed leveling it pushes down on the bedplate bending it alarmingly before failing. Done a couple of selftests, which passed, but the bed level is failing. 

Now to look around as see what I might have done to cause that.

RE: What sort of failure is this?

Your z-offset is too low.  Anytime you work on your printer you need to re-calibrate the z-offset, especially if you tinker with the hot end.  In fact, even if you just lift your printer and move it to another location you should re-calibrate z-offset.  Keep in mind that the difference between a proper z-offset and a bad one can be as little as 100 microns.  Based on the picture I'd say your z-offset is off by far more than that.

Cheers

-Bob