Didn't disconnect the battery during screen replacement

I followed this guide:
iPad Air 3 Screen Replacement

At step 12, it told me to disconnect/isolate the battery connector with a blocker/playing card. However I could not slide the card underneath so I proceed with replacing the screen which works fine (and displays) until I screwed the battery connector screw on. Now the screen does not work at all. Tried putting the old screen with dead lines back but no help.

The iPad still take charge and can connect to my PC, emit sound but won't display anything, any help is greatly appreciated!