The shortcut 'target' was:  "C:\Program Files (x86)\Armory\ArmoryQt.exe" --datadir="M:\Armory" --satoshi-datadir="C:\Bitcoin\"

Having removed all the quotes from the datadirs, its now working

And the /blocks was just me trying various options to get it working.

It would be nice if on an update, my shortcuts werent replaced.

What should I be putting in armoryconfig.txt so that I only need to set --datadir each time?