Xbox Controller keys trigger together

I have a 2-year-old Xbox controller from AmazonBasics, been put in the drawers for a year+. Recently I took it out and found a few problems upon using:

1. The right stick x-direction movement will also trigger y-direction movement (purely x-direction movements). x-left would trigger y-down and x-right would trigger y-up. This happens all the time.
2. The left stick y movements would trigger right stick x movements. That is, when you walk forward in a game, you'll always rotate left; when you walk backward, you'll always rotate right. This only happens sometimes.
3. The Right-trigger would cause character to walk right. This only happens sometimes as well.
4. The vibration unit sometimes not work.

Upon disassembly and cleaning, I was able to fix the first problem. The soldering blobs look fine. The latter 2 problems continue to exist. Need some help identifying the potential problem. I'm wondering if it's a motherboard problem that can't be fixed on my own.