There are several situations when your Schlage button might be blinking red: -Red light with two beeps while entering your user code - entered code is incorrect. -Red light after green light, together with high and low beeps while entering your user code - user codes are disabled via "Vacation mode". -Red light followed by green, together with unlocking delay when opening the door - battery is low on energy. -Constant blinking red light - the battery is critically low on energy. -Red light when adding a new user code - the amount of user codes exceeds the allowed amount. -Red light when confirming operation with two user codes or programming codes - the second code was entered incorrectly. -Red light with two beeps when programming the lock - an incorrect number entered after the programming code.