Well - just saved the day before heading off for long weekend in the Highlands. I had thought the spare would get some use, but I managed to sort the short (with lots of flux, and the smallest solder wick I have ever seen)

The RAM chips are still there, and all solder joints appear good - I just removed the connection to the ARM (and the solder mess I made around pin 123 etc) so at some point I need to redo that link. Pins 14 on the RAM still look strong so hopefully I can successfully do it next time.

Thanks for the advice Genixia.