How do you start Windows 10 in safe mode?

EDIT: The reason that the Windows 10 Boot manager doesn't work with f8, is because it has been disabled by Microsoft. to Re-enable it, follow these steps. (you will need a recovery DVD or partition available for your Windows 10 installation)

1. Power on your PC.
2. Use the appropriate key(s) to enter into the BIOS setup.
3. Configure your PC’s BIOS to use your recovery medium as the first boot device.
4. Reboot into the recovery medium
5. On the first displayed screen, click Next, and then click Repair your computer from the next box.
6. From the Choose an option window, go to Troubleshoot > Advanced options > Command Prompt.
7. In the opened command-line interface, type C: and press Enter.
8. Once the first commend executes successfully, type BCDEDIT /SET {DEFAULT} BOOTMENUPOLICY LEGACY command and press Enter.
9. In the command line-interface itself, this time type EXIT and press Enter.
10. Set your bios to boot from your Windows 10 installation again.
11. When your computer begins to restart, start pressing the F8 key repeatedly until you see the Advanced Boot Options menu.
12. Select the "Safe Mode" boot option

P.S. I think I found a solution to your problem here, apparently lots of people are having problems with "INTERNAL_POWER_ERROR" on windows 10.