You have 3 trials to enter your password correctly.
You must press C key after every trial of entering your password.
You must not press any key except C key before re-entering your passowrd beacause it will lead to an incorrect message which is counted as one of your three trials before system locking.
You can erase all the numbers and re-enter the password again before the fourth digit by pressing C if they are incorrect .
1111 for normal password
2112 for admin password