UAG Surface - Screen goes black when after restart

If this happens to UAG Surface machine, try this:

1. Press and hold Volume Up (on the left side) and the Power button at the same time for at least 15 seconds. This will restart the Surface in bios mode.
2. Select the option to exit from bios mode (or to restart the Surface). These options may vary depending on the CPU.

Source: https://thecellguide.com/what-to-do-if-your-microsoft-surface-pro-wont-turn-on-or-has-a-black-screen-of-death-4821