I have a Thinkpad T480, trying to replace the screen

Hi @todd85559

You may have got the wrong screen.

Depending on whether you got a FHD (Full High Definition 1920 x 1080) or a HD (High Definition 1280 x 720) will mean either a 40 pin or 30 pin cable connection between the motherboard and the LCD panel

Here's the parts list for the laptop.

Click on Select Commodity > LCD panels (16) to find the part number for all the LCD panels that are available. The screen type is shown in the panel description e.g. FHD or HD.

Usually the Lenovo part number is somewhere on the back of the original LCD panel if you wish to verify

Search online using the part number only to find suppliers

Here's the hardware maintenance manual that may also help.