laptop turns on for 1 min and shuts down after disassembly

[Manasa1995]

Hai I opened my brothers laptop to clean it. I thought I would do something wrong so I assembled everything carefully.I am sure I have not done any mistake. When I am trying to turn on the fan is rotating for 1 min and shutting down every time.Screen did not turn on not even for a sec . I checked 2 more times this assembling process . I sure nothing was done wrong. So plz help me to fix it

 

[Manasa1995]

MERGED QUESTION
Question from Manasa1995 : "laptop turns on for 1 min and shuts down after disassembly"

My laptop model is lenovo z580 .
As I mentioned earlier my problem .
I opened only hard disk, CD drive and keyboard I have not done any thing more than that .the connections the I removed are keyboard connections and placed them back

 

[hang-the-9]

No way to check anything since you took it apart without being there to look at it. Have a computer shop check it over, maybe you did not connect the heatsink properly or damaged something when working on it.