Car won't crank with both a good battery and starter

I had this problem a few weeks ago. I went to start crank it, and all I heard was the starter relay going wild. All the power in the car seemed ok, and the batery checked out ok. I thought it was the starter, so we replaced it, but it still did the exact same thing.
It turned out to be a faulty engine ground wire. That wire at the front of the engine that goes to the body… Well anyways, that thing is really weak, so I replaced it with a braided steel cable from autozone and made sure to connect it to both points on the block. It started right up.
Let me know if anyone else has had this problem.

My car would do nothing when you turned the key. If you wait for a few seconds with the key turned to “run” then it would start. Last weekend I cleaned the connection to the starter and the problem seems to be gone. I did notice that the ground you are talking about is starting to disINTEGRAte.