Cube orange didn't boot up after left being unused for 1 month

Hi there I actually had a little work so I grounded my cube orange based arducopter for almost 1 month but when I again wanted to fly I just connected everything else but it didn’t boot up.Neither it boot up nor it get connected to PC.
After many struggle I decided to unscrew carrier board and main cube, then again screwed them together again and guess what It again started working properly.
I dont understand why did it behave so.