You will be prompted whether you want to continue accepting will make you a permanent enemy of the Brotherhood and all Brotherhood related quests will auto-fail. Institute - Mass Fusion - Upon starting this quest you need to jump onto the relay to be teleported to the Mass Fusion building. I believe you are still able to fast travel there even at this point however don't expect a warm welcome. You will however get a new mission, 'Banished from the Institute'.
At one of the next quests (I believe it's Spoils of War) you will start to climb into a Vertibird and it will prompt you whether you want to prcoceed if you climb in you will become permanent enemies with the Institute and all Institute related quests will auto fail. You will not be able to pick up anymore quests for them or fast travel to the HQ). The following missions are when the story starts to split (or instantly splits) into the point of no return depending on what faction you want to side with īrotherhood of Steel - Tactical Thinking (as soon as you finish talking to Lancer-Captain Kells at the start of this quest you become permanent enemies with the Railroad and all Railroad related quests will auto-fail.
