Pixel 6a screen replacement failed - black screen

I replaced my Pixel 6a screen because I'd cracked my screen.
I followed the written instructions, but it didn't work. The screen is black.

When powering on, I feel the vibration, but nothing on the screen.

The video is a bit of a joke, edited to appear "fast and easy" when actually there is plenty of detail they could have included.

I tried reconnecting my old screen, but now that is black too.

Very disappointed :(
Help appreciated!