Computer hibernated during an update

[Wollie]

I would suggest first to try what is described here:

Boot file not found

Welcome to the forum! You are unfortunately not the only one to run into this problem. Many people interrupt the update process because they think their machine is hanging, and then they press the reset button. For other people, there may be other reasons why the update process gets interrupted, but an interrupted update will indeed leave you without a bootable kernel, because the kernel images are only properly installed during the last phase of the update process. What you n…

It could be that you need to install a kernel after the update command, for example if you want to use kernel 5.10, then apply

mhwd-kernel -i linux510

just after the update command in the linked post.