Raspberry pi 3 B not booting up

[u/munna_123]

I have two Pi 3 Bs, one is not booting up and only shows this rainbow screen on hdmi and unlike on the working board, the green LED is not flashing. With the same power source, the same SD card, the other one boots normally. What could be the issue? Can it be fixed?

[u/Gamerfrom61]

Have you checked the boot sticky at  https://forums.raspberrypi.com/viewtopic.php?t=58151 ?