iPad screen lock screen

Hi guys. I wonder if anyone can help me figure out what's going on. My 5 year old son got a password on his iPad which I know and set up. His teenage siblings yesterday was with him and know the password. Now when i try the password it goes to a buffering star screen for a second or two and then back to re-enter screen o CK screen. When I try wrong codes though the buffering screen doesn't come on