Lawn tractor Stiga Villa does not start

Moin, my turret Stiga Villa about 12 years old does not start. If I go with Plus on starter it starts, at the magnet switch also. Ignition lock also ok. 4Pol magnetic switch, there is battery on it, starter and on the other three red cables. 2 from the ignition lock, one red in the motor housing and two yellow. One yellow from the seat contact, the other goes to such a funny circuit board.There are no fuses. I go with mass on the one small pole at magnet switch and on the other In addition to the battery, it also starts. I don’t have a power plan. Know me, but don’t come any further. Safety switches are bridged. At the ignition lock 5 connections, mass, two red to the magnet switch, blue etc. The red cable coming directly from the motor housing to the magnet switch, for which is this ????Take some photos. On the magnet switch coming from the ignition lock, should be voltage or? But there is no juice, it would have to be a plus cable directly from the battery to m Ignition lock go?? This distributor board has also sunk