Doest start completly and in few sec it restart repeatedly

It does't start completly but you can hear the fan and HD works only in a few sec , then it sart again same before no boot or display on screen... btw the screen is already broken but i used tv as external monitor (i mention it so you don't need to suggest that the monitor is the problem ) and it works without hustle.. The problem only occur after i clean up the fan. I remove the fan carefully and put it back just like i normaly do every time i clean it up.