You fell for a common rental scam. Report to IC3 and be more careful in the future.

Only thing that doesn't make sense is how you gained entry. Typically this scam involves an "out of town/State/Country" owner who "can't be present" for a showing / physical signing. Normally you never get keys and aren't able to even get entry or look around the unit.

Was it just an unlocked vacant apartment? This sounds like some kind of inside job. Sometimes people leave apartments open and empty for showings, but what about keys? Something about this just doesn't make sense to me at all.

I'm betting you paid via crypto or wire transfer. Usually these housing scams are people paying an extremely cheap rent price sight unseen with some sort of fake ass E-mailed lease and a promise of mailed keys.

How did you get in bro? Were there even Keys? Sounds like you crawled through a window to me. Unfortunately you are completely screwed.

Getting a lawyer isn't going to get your money back, and with these online scams local law enforcement is likely going to be completely useless. Scammer is probably not even in the U.S. nevermind TX.

Unfortunately you are leaving out a lot of important details OP. But I have seen this scam 1000 times and your money is gone. You aren't getting it back. I'm sorry.

Hopefully you can avoid eviction by invoking some kind of squatter rights, but it's temporary at best. My tip is that you need to accept your losses and face that you are a common scam victim who has lost $4,000. Your bank will not reimburse you for willingly and knowingly transferring money to a scammer. It's gone.