I am so grateful to have found this forum and this topic.
I have an Asus N56JN and got the "Invalid Signature Detected. Check Secure Boot Policy" error.
Following the wonderful instructions in this thread, I did as instructed in the Youtube video posted above, created a Windows Media Creation Tool to create a bootable USB flash drive of the Windows 10 install disk.
I absolutely CANNOT lose any data on my laptop, so I did not choose to do a clean install.
I was able to use the flash drive to restore my computer to the last restore point, which was on June 2, prior to a critical update.
Now I am stuck. With the USB drive in, it keeps taking me back to the choice to repair the laptop or do a clean install. With the USB drive out, I have a black screen that says, "Reboot and Select proper Boot device or Insert Boot Media in selected Boot device and press a key."
Please help! Thank you so much.
Edited by britechguy, 05 June 2018 - 10:55 AM.
Split to dedicated topic and changed title accordingly