Yeah,try disconnecting the battery and also try removing the glovebox as the fusebox is behind there,see if there's something obvious like a relay dislodged etc.even try giving them all a tap first to see if the chattering stops.

If you can locate the chattering relay,try swapping it with an identical one in the fuseboard and try starting it then,just to get you there.

I have seen them with electrical problems before caused by water entering the windscreen and running into the fuseboard.mad I know but the screen came out and was resealed and the problem went away after the fuseboard was cleaned up.

Worth a look anyway,literally takes 2 mins.