Read the statement by Michael Teeuw here.
UNSOLVED Rainbow screen
I have no ideea what is going on. It worked perfectly until today. When i tried to turn it on this happened(i think it s rebooting). I changed the power supply , even i used the main one from raspberry pi 3 b+ , and it still oesn’t work. Any ideas?
sadly, usually means there is a problem with the sd card…
if u have another linux system , you might be able to repair it with fsck, maybe…