problem with not booting Linux Mint after kernel update

A couple of days ago, when I attempted to shut down Linux Mint 20.3 on the Macbook, there was no shut-down button visible on the usual shut-down dialog box. I thought this was some problem with the latest update, and thought that a restart would fix things. (That was a mistake, as you can see below). But after doing a sudo reboot from a terminal, the system would not boot up - it complained of a kernel panic, no working init found, and suggested trying to remove the init options. After googling some no working init found forum posts etc, thought I might need to check the disk for errors, but 

badblocks /dev/sda3

found no errors. Then I thought I would just try booting with another kernel - pressed F2 (more options) from reFind, booted with an older kernel 5.4.0-121-generic. Booted up with no issues. Tried doing 

sudo apt update
sudo apt upgrade

Then found the real culprit.

E: dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct the problem. $ sudo dpkg --configure -a
Setting up linux-image-5.15.0-41-generic (5.15.0-41.44~20.04.1) ...

Ah - so I was the culprit - Mint was not showing the shutdown button because the update was still in progress - I had somehow interrupted it. Anyway - running dpkg manually with the command above fixed the issue, and the system boots fine now with the 5.15.0-41-generic kernel too.