Is it just a case of plugging it into the nvr now and it’ll appear in the live view automatically?
OK - if you've already 'activated' the camera, then this is how to connect to the NVR PoE port :
In the NVR web GUI, for the channel you intend to connect the camera to, note down the IP address that's assigned.
As you've mentioned, it will be a value in the range 192.168.254.x
This is what you need to set the camera to.
You also need to decide if the camera is going to keep the password you have given it - or use something different.
Either way - that password needs to be set on that NVR PoE channel configuration.
On the camera - change the password if required. But it must match what's set in the NVR PoE channel.
Now change the camera IP address to be the value you noted from the NVR PoE channel.
Let the camera reboot, then power it off and connect it to the NVR PoE channel.
It should show up in Live View.
Going back a little bit -
Despite initial indications, it's clear this was a Chinese camera, running 'hacked to English' firmware.
Your initial 'refresh' of the firmware 'bricked' it, as is normal when applying stock EN/ML firmware to a Chinese camera.
The camera then went into the 'min-system recovery mode' where it shows in SADP with firmware version V4.0.8 and no web access.
You did need to recover it with the brickfixV2 convert / update method - which you managed perfectly well.
The confusing thing though was why didn't it simply just work after that?
Which you actually figured out for yourself.
So all's well that ends well.
And you'll have a serial console kit to play with some time in the future!