I'm using a Samsung Galaxy Book Flex 2 Alpha, and when I boot KDE Neon it just restarts.
I had the same problem earlier with Ubuntu 21 and other OSes, but it works on Ubuntu 20. Since KDE neon is based on Ubuntu 20 I'd think it would work, but it doesn't.
If anyone needs extra details I will be happy to provide them. Thanks in advance!

Post the BIOS event/boot logs.
Does a splash screen show for Neon - or just the manufactures sign of life splash?
Do you have any other OS' installed?
Did you wipe your drive and create a new EFI boot partition when installing KDE Neon?