Join Date: Aug 2017
Location: Perth, W. Australia
Can't be specific, not enough info, but it's a matter of trouble shooting. Does sound like a relay issue, if it is faulty, it will hold the connection ie. bike still runs, but when turned off, it can't reconnect.
1. check battery, is it fully charged?
2. check battery connections, are they clean and tight
3. check all fuses with new ones if possible.
4. Does the bike crank over?
Also I don't have a 620, but there are 2 small relays next to battery, on other Ducati's I've had they are the same. Try swapping them after removing and cleaning connections. Relays should give a little click when on, if in doubt have them checked and/or replaced. From memory, one works fuel pump and other things, the other has to do with instrument cluster, ignition etc. Swapping them may get your dash to work. Then you know one is bad.
Electrical problems can be difficult to find unless you have testing tools.
hope this helps,