Never installed a Norton software under Win10 but I had keyboard and mouse not working under safe mode.
This WE I solved my problem but I don't know how.
I breaked my Marvell RAID0 and after some restores using Acronis 2016 and using WinRE boot fix, as original restore was not able to finish the boot, I was able to boot to my desktop.
At this point in safe mode both keyboard and mouse are still not working, but I noted that drivers of mouse and keyboard were reverted to Windows 10 default ones.
Then I used the original Win10 1607 x64 image burned in a DVD to do a refresh of installation, keeping apps and personal files.
As soon as it finished its job, I have luckly the keyboard and mouse working on safe mode!
Probably Windows installer this time detected something wrong on driver management and changed it to default clean installation procedure.
Unfortunately what I did is not a solution but a miracle that worked in my configuration.