Waveshare Game HAT Case Remix with lockable lid

First of all, thanks to Zuendy for it's great design. I've modified the backcase for rev. 1.2 (with square shoulder buttons) to include a lockable lid to access the Raspberry board and the battery without needing to unscrew anything.

Also added a ventilation grill and resized the shoulder button holes to avoid them to stuck when pushed.

UPDATE: Added button cover without text.