no keyboard/trackpad inside OS, but works in BIOS

i just took in this dell inspiron 7737

everything seemed to work fine except the trackpad wasn’t clicking. tracking worked fine.

i disassembled the laptop to clean everything out and see if the clicker offered any adjustment. no adjustment, but i cleaned everything out and made all of the connections.

now i have no input in windows. i can F2 my way into bios, navigate around in there, but as soon as OS loads, i only have the touch screen. i have checked and reseated all cable connections. the only thing i can imagine is that all of the case screws are needed to complete a ground circuit?

i don’t want to put this whole thing back together if it needs more work…