Hi Holger, here is the schematic for A2 model. I chose this one because I don't know what model do You have, but on this example we are going to follow simple logic to determine the location of the fault in the starter and ignition circuit. In the description below colours written in brackets mean the real colours of the cables in the bike model A2 US and Canada. I have marked relevant part of the circuit on the picture with green, red and green-red line. Now follow the line starting from: the battery plus (red-white) to 30 amp fuse, from there to the main switch (white-black) highlighted yellow, from here to the ignition switch (white) highlighted blue, and from there to engine stop switch (brown) highlighted green. Between the ignition switch and the engine stop switch there is a branch leading to the oil pressure warning light marked red, so when the engine has quit the 12 volt power must have still been there, because like You said the lamp was still on. Now going backwards from the igniter (yellow-red) towards the resistors then past them to the engine stop switch there must have been no power in that wire since the engine have died. Now: notice the branch (under the switch icon on the schematic) just after the engine stop switch: one to the resistor and igniter (yellow-red), wire marked RED, and one to the starter lockout switch (black white), wire marked GREEN, there was also no power in there when the engine have stopped, because the wire going down TO the lockout switch (black-white) is coming out of that branch, than going back up to the starter button (black-white). So this explains why the starter button did not respond when pressed. By following the logic I conclude that the problem reside between connector for the dash lights and connector to the engine stop switch and starter button including the switch itself, I marked the area with red-green, both switches are placed together in the right hand switch module. Its difficult to say what exactly is causing a weak connection but at least that's where I would start to look. Any way I to have probs with electrics on my bike so when I'm at it I try to make some pictures and trace the wires of You interest, till than ride safe Holger !!!
Sorry, picture quality is crap but that's the best of me in front of the keyboard. You gonna have to use pdf manual for details page 297-297a.
Darek