Iphone 4s iOS 5.0.1 Screen lock code brute force.

First Has anyone attempted a brute force attack to unlock 4digit pin on iOS 5.0.1. Or anyone has experience using IP box on iOS 5.0.1 with any positive results.

The device is iPhone 4s and no backup is available.

Second I have a dummy iPhone 4s to test but the iOS on it is 9.3.5. If anyone has any knowledge of downgrading it to 5.0.1? I have a procedure to go back to 6.1.3 but not a version before that.

Ideas are welcome.

Peace.