Thanks for posting here in the community. To confirm, do you have the battery or wired type of Nest Protect?
Give these steps a try to force update your Nest Protects:
a. The LED will begin to glow blue - this can take up to 20 minutes, especially for a software update.
b. If there is no update, the LED will glow blue for a couple minutes.
c. After the Protect’s LED stops glowing blue, it will briefly glow green, then turn off.
Note: The LED ring may glow yellow instead of green if there’s an error when trying to check for an update or if the Protect can't communicate over Wi-Fi. If the Force Update is unsuccessful, the Protect may speak, “Please try again later.” This means the Protect couldn’t connect and might indicate that there's something wrong with the Wi-Fi network.
Keep us posted.