Trackpad doesn't click and is acting weird

I have used a external mouse for my macbook (since i bought it) it had the problem when i bought it (the seller unplugged the trackpad from the motherboard and said it didn’t work) now today i decide to plug it in and it worked but it does not click (battery is not swollen) it goes down but it doesn’t register on MacOS, and sometimes when i’m scrolling it thinks i tapped with 2 fingers (registering as a right click) does anyone know what the problem might be?