Screen is not displaying properly after port replacement

I recently opened up my Pixel 3a using this guide (Google Pixel 3a USB-C Port austauschen) and replaced its USB C port.

I've reconnected the screen to the phone using the flex cable and I turned on the phone before gluing it back into place to test it. The display isn't working; I can turn it on and see 'shadows' of what it's trying to display (like the home screen or the 'power off or restart menu' when I hold down the power button) but on the whole the screen is black and the phone is unusable. The touch screen functionality still seems to work. The charging port works as well.

Does it sound like the screen itself is damaged, or did I damage the connectors somehow? I’ve attached photos of the connectors. Thanks in advance.