How to adjust the mechanical handbrake of a 2019 Kaiyi X3? How do you remove the handbrake cover? Any advice from the experts would be appreciated. Thanks!

I adjusted the rear drum brakes by removing the tire. There's a hole at the bottom center, and you use a flathead screwdriver to move it up or down. If the wheel hub doesn't turn, adjust it back a notch or two until it turns freely. A slight friction is fine; it'll wear down and stop making noise. Don't make it too tight, or it could damage the brake pads and increase fuel consumption.

Pull apart the area behind the USB location.

I also need to adjust mine, but I don't know how to do it.

I have the same issue, mine needs adjustment too, it's not tightening anymore.