Can't upgrade beyond El Capitan - screen unresponsive

I have an old MacBook Pro mid 2012 which had a broken screen. I sourced a replacement screen from a dead laptop and fitted it, but it has SUCH an odd issue.

I can install any version of OS X / MacOS from Mavericks to El Capitan and it works absolutely fine. All hardware tests OK both in the Apple Hardware Test and using Tech Tools Pro

If I upgrade or fresh install MacOS Sierra, High Sierra, Mojave or Catalina, the installer runs absolutely fine, until the final reboot when it runs the welcome routine. It gives the Apple logo, the progress bar goes until about 90%, and then it goes no further. The mouse pointer is visible and moves, and the voiceover starts with the ‘welcome to MacOS’ announcement, but the screen output will not progress beyond that.

I did try ensuring my user account had no password in El Capitan and upgrading to Catalina so I could log in without having to put a password in - there was a thread on the Apple forums about a similar issue which was bypassed by entering your password and pressing enter and the desktop appeared. No suck luck for me though…..

I’m a bit stuck on how to proceed. I don’t *think* it’s hardware related because everything works fine up to El Capitan.

Thanks in advance for any ideas.