Anika the Aardvark

why would you even open a 12 Pro Max anyway, seems like a lose lose, even if you’re trying to replace the battery, just pay Apple the £79 and have a brand new OEM battery

Will apple do back glass and battery without fixing the screen? I'd rather fix the screen myself for less

Rear glass is Apple getting an entire new housing, swapping the board over, and repairing EVERYTHING in the housing, including FaceID hardware and cameras. Apple junks your old screen and housing. Even if the front glass and OLED isn't damaged.

So does this mean they'll essentially replace my phone for £80?

You should get the equivalent to a refurb, as if you are buying the device refurbed by apple, except you know where this logic board has been lol

Even if the display is broken?

Yes, although they might charge you for the display if it's broken

I honestly can't tell you, unless i see the phone and the story you want to tell the tech, and is this applecare +?