For now I get rid of all the cables. Today after work I will also get rid of the alarm.

I guess next season I will bring the bike to a repair place and they should get the electric done probably.

edit: This one is the Alarm System: https://www.buggycity.eu/product_inf...d--roller.html

It's in german sadly. It says that it got a proetction for manupilation due to a emergency battery.
It uses 4mA in standby OR when it's turned on.

Edit: Also found the Manual...it says that the Alarm System is draining the battery empty after 2 weeks if the motorcycle doesnt get moved. So as a conclusion...i am 99% sure that the navi cable AND the Alarm System managed to drain the battery within 1 week empty. It still was enough to start it but I couldnt start it again after the stop at the gas Station. The Problem is, if the battery (it MIGHT be a type AGM one) is completely empty it can't get charged by the lightmachine therefore...the engine stopped working as soon as the laste Piece of voltage was used (after the Mercedes guy bridged it). That would explain all of the Troubles.

After work i will put the battery back in...get RID of the Alarm. JUST the motorcycle electronical stuff and nothing else (okay i Keep the grips but just because I have no idea where they are plugged to ). If it works fine then and I don't get any Trouble in the upcoming weeks (I will not ride for 1 Week atleast and check if the battery lost any power) I might put back the navi cable or the Alarm. So i can eliminate the Trouble causing parts.

and btw, i stopped putting all the capitals down haha, german stupid Keyboards and Computer Keep automatically put capitals on most words. Im just tired of manually changing it back xD Sorry