Interrupting an upgrade may leave your OS in corrupted state.
No one can tell you how to fix it; indeed most of us would just restore from backup or do a fresh install.
In fact there is NO RECOVERY partition on a normal Raspberry Pi OS OS.
If you want to attempt recovery of your data use a fresh SD Card.
"how would I attempt recovery with a fresh SDcard?"
You can do this on any Linux computer (including the Pi using a fresh install of Raspberry Pi OS).
See https://raspberrypi.stackexchange.com/a/102090/8697
Unfortunately you have used NOOBS which makes everything more difficult (including the fact that most recovery hints you may find don't work).
The boot and root partitions will not be 1 or 2 - you will have to determine these.
sudo fdisk -l /dev/sda
should show the partition layout.
This will enable you to recover your home directory.
You could try accessing files in the root partition, but this requires more expertise and, frankly, most experienced users wouldn't bother as it is risky and more work than doing a fresh install.
"I have a NOOBS recovery partition. Could that help?"
Absolutely NOT - this is to do a fresh install, and would wipe everything. Fortunately NOOBS is now hidden, and only used by some vendors.
init=/bin/sh
to yourcmdline.txt
file (in boot) if the Pi would at least boot enough to see what the issue is – Bravo Sep 11 '21 at 01:09