Failed Battery Replacement. 2017 MBP CPU repair store cant fix either!

My 2017 15” Touchbar Macbook Pro was in good working order, battery life was meh, so I bought the battery kit, replaced it.

However upon what I thought was a successful replacement, the computer failed to power on, or even charge. I took it to a computer store and they attempted to replace a flex cable they said was under the main logic board that was torn, which did not fix the issue either.

they have since given up and only charged me a diagnostic fee.

any suggestions?