HDD Unknown Problem

This is the problem hard drive I talked about in 系统盘迁移小记.

Before I took it apart I assumed the problem would have been  some head stuck on the disk according to the noise. And I did try to knock it against the table, with no luck.

So when I finally decided to take a risk and opened it... It just sucks. I was completely wrong and I still have no idea what's the actual problem.