If it flashes red while walking past it, the battery is low.
I had the same with my keypad, contacted support and told them about it. Turns out the app is not in sync with the battery stats of the keypad. I got a low battery notification for the keypad about a week or so after it started flashing red.
I did look it up in the manual and it does state that flashing red when walking past it means the battery is low.
My keypads are working fine now after recharging and after the update.
So please recharge the keypad and try again.