How to change a battery in a Schlage Keypad deadbolt Lock

Schlage locks can blink red for two reasons: a red blink followed by green indicates low battery and the door will open; a steady red blink with no opening signals issues like dead batteries, incorrect user codes, programming errors, or a nonworking keypad. Fixes include replacing AA/9V batteries (remove covers, swap batteries, reconnect), reentering matching user or programming codes, deleting and re-adding user codes if full, using a physical key if the keypad fails, or performing an emergency 9V jump-start to unlock and then replace batteries.