For troubleshooting, your wireless Magic Keyboard and Magic Trackpad can work over USB-C if needed, but if Bluetooth or pairing fails when you’re booting into macOS Recovery, an old or cheap wired USB mouse and keyboard can save the day.
Tag: USB-C
Not sure if your USB-C cable is delivering power and data as it should? USB-C cables look similar but may work differently. Use the free WhatCable app to see what each of your cables supports.