Being stupid, but it might help someone!

I assembled the 420 in the house, linked it to the PC and jogged it around a bit. Now that the weather is warm enough I moved it to the (unheated) workshop and got ready to start making sawdust.
Error message "Machine not ready". LED's were lit, checked all connections- all OK. Uninstalled and re-installed the software- same error. Was just about to look for help here when I noticed that, in carrying the machine out to the workshop, I must have pressed the emergency stop button which locks in the off position. Released it and all is well. Creations will appear shortly!