Why would the GPS not be working after a screen/battery replacement?

Hi everyone. This is my first post. I figured I'd come on here and see if anyone knew more than me about the S9.

I fixed my girlfriend's Galaxy S9 with parts from InjuredGadjets.com. I got a new display+frame, and a new battery since hers was shot, barely lasting an hour on a full charge. Ever since I fixed it a couple months ago, her Google Maps is unable to navigate due to a lack of a GPS signal. The marker/arrow that indicates us/our vehicle turns gray and the app says "Searching for GPS". Eventually Maps will just give up and verbalize "GPS signal lost". We've tried wiping the cache, both from the partition and the app itself, force stopping Maps, starting the S9 in safe mode, and I even tore the phone down again and made sure ribbon cables were seated and re-seated them. Still nothing.

Am I missing something here? Maybe I missed a ribbon cable somewhere? Do the antenna cables have anything to do with the GPS? Her data signal is fine, and she can still make calls.

I also read that sometimes 3rd party batteries can cause this issue. Is that true? Maybe that's the case. The battery is an XCap or whatever.

I really appreciate any guidance on this. The initial repair of the phone was easy, but this issue definitely should get fixed. Last week there was an accident on the road and she struggled to get home from work because she couldn't use Google Maps. Usually I'm the one who drives us around and navigates using my S10e with Android Auto, but this should still definitely get fixed in case of an emergency.

Thank you for your help!