Won’t restart after update

What blinks? 

The power light? If so, you might have corrupted the firmware. 

You can try recovering it with tftp or nmrpflash.
are you on windows? if so, follow this guide
https://kb.netgear.com/000059634/How-to-upload-firmware-to-a-NETGEAR-router-using-Windows-TFTP
just make sure you enable tftp
https://www.thewindowsclub.com/enable-tftp-windows-10

and here's a video walk through using a tftp client. Use the built in one for windows 10 though. the video is more of an example of how its done.
https://www.youtube.com/watch?v=R9DLrLQrpaw

and if that doesn't work, you can try using nmrpflash
https://github.com/jclehner/nmrpflash

What model Router do you have? 

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Dexter12 wrote:
Just tried to update security on Router, now router only blinks and will not reboot?

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