If you can’t access the UEFI during the bootup (e.g. via F1, F2, F8, F10, Del or Esc), it’s possible that it has fast boot enabled.
Solution
1. Start Windows in PE mode:
Settings –> Update & Security –> Recovery –> Advanced startup –> Restart Now
Alternative with CMD: shutdown.exe /r /o
2. Goto UEFI and diable fast boot:
Troubleshoot –> Advanced options –> UEFI Firmware Settings
If there is no “UEFI Firmware Settings” entry, it’s possible that the system hard drive is using MBR (Master Boot Record). If that is the case you have to switch to GPT (GUID Partition Table) to be able to enter the UEFI.
Solution
1. Start Windows in PE mode:
See above
2. Convert MBT to GPT:
Troubleshoot –> Advanced options –> Command prompt
mbr2gpt /convert