The screw and required driver are NOT T4 but Torx Plus 3IP (Torx 3 will do the job) according to the MS Service Manual (856727 Microsoft Surface Surface Pro 8 Service Guide - linked at the product page here at ifixit.
For model A1229, you have to disconnect the two additional connectors. Both are small with a black and grey cable, like the one in the top middle on the photo.
The first is located between the large display data cable and the fan connector, the second is located near the two connectors marked at the top left of the picture.