Can't get Asus X551C notebook PC windows 8 to boot windows has black screen with an arrow that can be moved with mouse

Solution
Have you tried booting in "Safe Mode"? I would try that first and see if it will go through. If it does, then there is something on the computer that is restricting your access in normal mode, and you will have to fix that issue.

How to enter "Safe Mode" when booting the computer.

In Windows 8 and 10 ...

As your computer restarts, press F8 (possibly a few times) to enter "Safe Mode"

a. Press the "F4" key to Enable "Safe Mode".
(The computer will then start in "Safe Mode" with a minimal set of drivers and services.)

b. Press the "F5" key to Enable "Safe Mode" with Networking.
( Once "Safe Mode" with Networking starts, Windows is in Safe Mode, with additional network and services for accessing the Internet and other computers on your...
Have you tried booting in "Safe Mode"? I would try that first and see if it will go through. If it does, then there is something on the computer that is restricting your access in normal mode, and you will have to fix that issue.

How to enter "Safe Mode" when booting the computer.

In Windows 8 and 10 ...

As your computer restarts, press F8 (possibly a few times) to enter "Safe Mode"

a. Press the "F4" key to Enable "Safe Mode".
(The computer will then start in "Safe Mode" with a minimal set of drivers and services.)

b. Press the "F5" key to Enable "Safe Mode" with Networking.
( Once "Safe Mode" with Networking starts, Windows is in Safe Mode, with additional network and services for accessing the Internet and other computers on your network.)

c. Press the "F6" key to Enable "Safe Mode" with Command Prompt.
(In "Safe Mode" with "Command Prompt" starts Windows in Safe Mode, with a Command Prompt window instead of the Windows interface. This option is mostly only used by IT professionals.)

Now sign in to the computer with your account name and password. (If you have one set.) When you are finished troubleshooting, you can exit "Safe Mode" restarting your computer.
 
Solution