Welcome to the forums!
Sorry that it couldn't be under better circumstances though.
Not sure how much it can help, but if you just want to go through some standard troubleshooting ideas, considering contacting your local ASUS support as well.
If your system power light actually goes out though when you say it very briefly powers off (rather than just the screen going black), it is sounds more like a hardware issue to me which is a little strange that it would coincidentally occur after your clean install though, so we may also want to check if anybody has better ideas too.
It could explain why you are not able to get into the bios, but that could just be the secure boot setting doing that as well.
Try tapping the 'ESC' to see the boot menu or 'F9' (which doesn't always work?) after powering on the unit to see the Windows advanced startup menu as well, but if you are not able to get into the bios or boot to USB, it can be treated like a hardware problem since there isn't anything else to try with software.
If you want to try some hardware troubleshooting, unplug the AC adapter and try to hold the power button from 10 to 30 seconds (if the unit powers on, it should power off eventually) before powering it on again, but don't have much hope this can help, and may not be good for your hard drive or Windows installation if it's really trying to boot.
If you're under warranty, you may want to consider sending it back for repair if nothing else works although if you can remove the hard drive, swap memory, or unplug the battery safely, those are a few more things to try.
Good luck!