Issue started after an automatic update. I was on a flight and had to put the laptop away, so I just closed the lid to sleep it.
Next use, it tried to restart and was stuck at the notorious 12%. After 15 minutes it would go to sleep, and the cycle repeated.
After several cycles, now it goes straight to the Failure Configuring... page. It has been sitting there for hours.

This is an HP Pavilion g7 with Windows 8 preinstalled. It didn't come with a boot disc. The security software is the Norton package that came preinstalled. No actions produce a response. I can't get to Desktop by putting the cursor at lower left, can't open the Search and Power menu by going to upper right. Swiping in from left or right does nothing. F8 does nothing. Windows + R does nothing. I can force a shutdown by holding the power button; afterwards powering on goes to the hp logo briefly, then I'm back where I was.

2nd question, if I can somehow get the computer to respond, can I install an earlier version of Windows, as W8 simply does not work reliably?

This issue could have occurred due to these reasons.
1. Corrupt Windows Update Components.
2. Conflict between third party applications or external devices.

Note If this issue occurs, it may take about 30 minutes to revert the changes, and then the system will show the Windows logon screen.

I would suggest you to try the steps in the article and check if it helps.

Error: Failure configuring Windows updates. Reverting changes. Do not turn off your computer when you try to install Windows Updates

Note:
When you perform System Restore to restore the computer to previous state, programs and updates you installed are removed.
Please do not perform in-place upgrade or re-installation of Windows.
After clean boot troubleshooting step, follow the section "How to reset the computer to start as usual after troubleshooting with clean boot" in the provided link to return your computer to Normal startup mode.