Hi @koniety ,
You may have to open it up again and check that the screen flex cable is still securely connected to the motherboard and also that the cable is not damaged in any way. It is very close to the battery at one end and you may have dislodged it or damaged it when removing the battery.
Here’s the Ifixit [guide|123458] guide.
Scroll down to view the image at Step.26 to see where it connects. Also Step.33 shows how the flex cable runs under the battery