I have a 4 years old dell e1505. It will feeze after running for a while, and I suspected that the cooling system is not working correctly because of all the dirt. I disassembled it and cleaned the cooling component and cpu fan. After reassembling it, my laptop won't turn on. When I pressed the power button, the three green lights on the left (I think they are number, shift and one with down arrown) , and the power light will turn on. After 2-3 secs, they will all go off. Can anyone tell me what this means? is there anyway to save my laptop?