for this thing I could have suggested chroot but unforutnately
so in that black screen I would ask you to try to go to some tty if possible by shortcut keys like
ctrl+alt+f1 to ctrl+alt+f12
because I have noticed that sometimes the login screen is opened up in any other tty and we are on different tty, even if you don’t get the login screen but you are able to get into tty terminal , from there you might be able to start the GUI and do chroot or re-installation