So I have an MBP15,2015. Its startup disk was accidentally set to windows. There are 3 major problems that will basically get me fired:
My ctrl key on the internal mac keyboard is stuck (logic board issue I guess, been there for a while). I disabled the problematic keys using sharp keys on windows & Karabiner on MacOS
Boot camp. exe /assistant does not show up in the notification tray area. Even running it as admin literally does nothing
Combine 1 and 2, I have no way of going back to the Mac partition because I cannot hold the option key, I cannot boot into recovery, I cannot do anything.
My only hope is the command prompt. I'm dead because I have around all my project in Mac and a meeting in 3 hours.
21 Answer
Hold Cmd/R at boot which will take you to Recovery.
From there you can access the Startup Disk control panel.
Your alternative would be an external keyboard.
If your macOS boot drive is APFS, windows cannot see it, so you have to do this at boot.