My Prius shows a Green Key Symbol and doesn’t start if I push the Power button

[mo_chiptu]

Hi. My Prius won’t start because of the green key symbol that shows up on my dashboard. It happened this Sunday when I pushed the power button and the brakes to start my Prius, this time it’s different. It shows a green key symbol instead of showing nothing in order to start. I pushed the power button and the brakes again, but it still showed that green key symbol again. No matter how much I pressed the brakes and the power button, it will show that green key symbol again.

I thought my key fob Battery was dead, so I replaced the Battery with a new one, and it worked. Until today, it happened again. 

However, I took they key out of the fob, and this time, it started with no issues. So… is it my key that’s causing the problem or there something wrong with my key fob that doesn’t work. I have a 2012 Prius C with a Smart Key. Can anyone help?

Edited September 29, 2022 by mo_chiptu
I don’t want to confuse anyone about the battery on my car or the key fob itself.

[TonyHSD]

Hi, 

your car immobiliser has not read the key for some reason most likely. Sometimes can happen if you keep your car key fob together with other keys with microchip or close to credit cards or remote controls for parking gates etc. If it happens again, take the key fob of your pocket or bag, hold it and push the start button with the fob itself, it should work. Similar things has happened to me too for no obvious on first sight reasons. 
Hope it helps. 👍