Here's my problem:
"I have an Asus Notebook X501A and it has just happened to me; I am running Windows 8.1 and I have done nothing at all that may have caused this.
Here's what I did that was succesful:
1/ Select the Boot menu in the Aptio setup utility, select 'Launch CSM' and change to enable
2/ Select the Security menu n the Aptio setup utility, select 'secure Boot Control' and change to disable
3/ Select Save & Exit and press 'yes'
4/ Hold down the power button until the unit switches power off completely
5/ Switch back on and continually press the F9 button for about ten seconds; this should now allow the unit to boot up into the Windows Recovery menu
6/ Select 'Advanced Start Up' and wait until the recovery menu appears
7/ Select ' Advanced Options'
8/ Select 'System Restore' and select a date prior to when the problem occured
System Restore worked perfectly for me; good luck"
When I tried to apply these instructions I found the sequence to be backwards. When I tried to 'Launch CSM', it said I must change the 'Secure Boot Control' to disable first before launching the CSM. Then, when I went to the Security tab to change the 'Secure Boot Control' to disable, there was no such option.
I ran 'Aptio....' through Google search and found the same solution you presented, but in a different article. Still at a dead end. I found the "remove the battery" option also in the same article.
If anyone has Asus related experience with this problem and have managed to disable the Secure Boot Control after not finding the option to do it under the Security tab, please let me know how you did it.: please tell me how to disable the 'Secure Boot Control'. Thanks.