Hello, I am new to 3d printing world I have decided to get myself my first printer the Ender 3 v2.

I was studying 3d printing for weeks and I chose this printer for it affordable price and good reviews.

I ordered printer of Aliexpress and it arrived in 7 days to me. I never assembled a 3d printer before but this wasn't hard to assemble by following youtube video. It was all pretty strait forward until I put the printer together and turned it on. The tutorial video I was following stated I need to ''Auto home'' my printer so I did. But when auto homing the printer starts thumping and vibrating hard and stops. I tried googling the problem and thought my Z axis rod might be out of alignment and after completely pulling it out and re attaching Z axis motor with some washers for spacing my Z rod was straight, but it was still hard to manually move Z axis by hand but not by screw coupling. So I adjusted the rollers  a bit and I can now move the Z axis by 1 finger up and down with little force but the printer still thumps when I try to auto home it. I don't know what is the problem, is my printer defective? And if yes what should I do try to return it or what? I did get warranty card with the printer , or should I try to contact the seller I bought the printer from on Aliexpress?

Video of problem:https://www.youtube.com/watch?v=6L1UafaxtJ8