No Service after rear, screen AND midframe replacement

I replaced cracked and/or dented parts on my s9+. Phone was working just fine before other than a lot of cosmetic damage. These include:

Back/rear glass

Midframe

Display/screen

Ever since the cellular signal strength is just awful. It exists but only in some rooms of my house and very week (-135dBm to ~ 110dBm if lucky). I was very careful with each part, and even did a full teardown to make sure no oils/dust/fingerprints were on any surface. I also replaced the antenna cables (the 2 blue and white cables) and no difference.

This cell issue is the only problem, wifi/nfc/bt all work just fine. And charging/microphone/speakers etc also work fine.

Any ideas on what part this could be? I did notice that the replacement midframe from ifixit has powder coat/paint in some spots where the original samsung midframe had some exposed aluminum as well as what look like conduction points/contacts. Does the midframe play an antenna boosting/connective/conductive role for cell signals? or might i just need to look at things like the charging board to be replaced?

Thanks!

EDIT:Images posted below of the original midframe’s ‘contacts’(?) Im curious about

None of the coppery/non-coated parts in those pictures are present in the replacement midframe. the replacement metal is 100% painted/coated