Open Nothing Phone (2a)‘s Settings.
Go to System and then click on System Update.
The device will check for the new version and download it.
Once downloaded, install it. The system may reboot during this process.
After the reboot, unlock the screen to access the lock screen.
You should now see the Nothing OS 2.5.4 installed on your Nothing Phone (2a).
Explore the new features and improvements introduced in the latest OS version. (All Images from Nothing official Website)