These might help, though they are not for your specific motor. I would start at the ignition switch with a voltmeter.
https://forums.pelicanparts.com/bmw-r1100s-r1200s-tech-forum/835898-wiring-diagram-r1200s.html
https://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/kwiring/K1200RS.SLP.Wiring.V1.0.pdf
or peruse this
https://www.google.com/search?sca_esv=577649933&sxsrf=AM9HkKmPZs8AceakRR0O3Dtz0zSh3F3IlQ:1698607531688&q=2020+bmw+r1250r+electrical+wiring+diagram+pdf&sa=X&ved=2ahUKEwifwKeU_puCAxU2GFkFHREWDhAQ1QJ6BAgrEAE&biw=1410&bih=1088&dpr=1.2#vhid=BhaZ3EjPmoBMhM&vssid=l