During the update process the computer just crashed and nothing helps (not even Reisub). Caps lock flashed. After a hard reset I cannot boot the system.
Error: premature end od file /boot/vmlinuz-6.7-x86_64.
You need to load the Kernel first…
Please help.
Welcome to the forum! 
First of all, note that I’ve moved your reply to a new System Updates topic for further troubleshooting.
No such thing. Define, please.
That’s indicative of a hardware failure.
Please see the following to help us help you:
If the system was in the midst of an update, at least the kernel is now missing.
… first the to be updated kernel gets removed, then the update …, then the new initrd is created at the end
interrupt the process and you end up with no initrd and kernel
This is easy to rectify:
boot from live usb and chroot (manjaro-chroot -a) into your system and run the update again