HELP!!

I bought an e-bike recently and the brakes were squeaking and took very long to stop. every time the wheel went round it was making a loud noise. I put in some new brake pads and renewed the oil in the brakes but they are still squeaking and take long to stop. The wheel is also very stiff when you try to spin it manually. Please help as I spent a lot of money on this bike. Any helpful ideas will be appreciated.