Transmission not working

So I just finished with my engine swap on my 2001 325i auto and the engine runs perfectly, the trans seems to be making a lot of noise almost like a whining noise. I go to back it out and it felt like it was slipping. I drove it for a bit but the trans seems to be slipping a lot more, I limped it back to my driveway and it couldn’t even go up the driveway even at full throttle. I did take out all the old trans fluid and put new stuff in. When I put the new fluid in I started the car and...

Transmission not working