IST'S NICHT EIN VENTRA APP?

German engineering has not yet come up with the fail-safe ticketing machine.  Was tun, wenn der Fahrkartenautomat kaputt ist?  Sometimes it's simple: look around the station for a functioning machine.  They usually come in bunches, just like bananas and buses.  The Germans have more attended stations than Passenger Rail operators in the States do, and there might be a station agent to help you.  If those options fail, take a picture of the malfunctioning machine with your Handy, and if you have to run and catch the next train, that picture plus an explanation will get you dispensation from the collector to buy your ticket at your place of departure.

It must be that a German public service announcement works like a German sentence: you have to wait for the verb.  Or in the case of the announcement, to learn about the equivalent of the Ventra app.

Mit der App DB Navigator kommen Sie gar nicht erst in die Bredouille, dass Sie sich am Bahnsteig wegen eines defekten Automats kein Ticket kaufen können. Kaufen Sie Ihr Ticket ganz einfach mobil und haben es als Handy-Ticket immer dabei.

Just hold up your Handy for the collector to scan the ticket.  In Germany, your ticket will be good on Regional or Cross-Country trains.  Amtrak or Metra or Ventra have yet to offer that convenience.