Chart update in ERROR state

OK, my mistake and the voltage dropped* whilst doing this weeks update on the 540.

On powering up again, there was a message that the chart update didn't complete successfully, and retrying the update process just gets to the same state as before (the update goes into ERROR state just after hitting 10% complete).

Reasonably enough, the charts are now unusable

Anyone know how I resolve this (the manual has the rather frightening statement that ".. a service action may be required..") - we were planning to leave for Osh in 12 days time, and there's not going to be a chance to get to a dealer even it they have an available booking before then

EDIT: Software level 10.2.3.1

* Dual batteries, but ground power only supplements #1 - I had #2 selected

Thanks Steve

Does this help?  I took a log download too before shutting down (although to the untrained eye, there doesn't appear to be anything significant in the event log)