Prevent Endless Reboot after Updating your Apple Laptop's macOS, especially the macOS High Sierra 10.13 Supplemental Update
If you have a MacBook pro and you want to do the latest update (the small one after high sierra, or "macOS High Sierra 10.13 Supplemental Update"), you should probably 1. backup (e.g., time machine), 2. (important!) connect your laptop with ethernet, and 3. connect to a power source. My MacBook pro time-jumped to some time in 2016 after the update and it forced itself into a power-cord only endless reboot mode. No kidding! Endless reboot, like you never hear the reboot sound effect so many times. After the update, it wouldn't start unless it was connected to a power source, but it would reboot a few seconds after that Apple loading progress bar reached around 60% or 90%. My current working hypothesis is that it has to be connected to the internet before it reaches that point. Otherwise, it restarts again before you could quickly choose a WiFi access point and enter the password. After a few hours trying all the special hotkey combinations suggested on the inter