Help my computer is not starting up there is a flash sign that keeps blinking next to the power and cd signs?

ok so my computer was working properly i like blew in the fan and everything so it can get rid of the lint and run smooth which i always do but now when i try to start it up it wont start up i dont know why its like this lighting thunder shaped thing that keeps blinking on and off it worked just fine before it is an hp chrome laptop i got it like not even 3 moths ago and the ac adapter and everything is working fine its brand new please help