I have a problem with an old qosmio laptop. It was overheating so i opened it up and cleaned all the dust inside. When it assembled it back, it doesn't power up. The laptop doesn't have a battery so it must be constantly plugged in. When i plug it in the battery led lightnens up but when i press the power button it turns off and nothing happens. Any ideas what can be wrong?
Only clue here is that it happened after you opened it. Most likely thing something is not connected properly or you broke a connector or something off the motherboard. No way to know without opening it up and checking it over. Reseat the RAM as well.
I've assembled computers in the past without any problems so i have a little experience.
I made sure everything is connected properly, thats why it took me by surprise.
Ram, video card , everything sits alright. I'm gonna check the connectors again hoping i didnt do any damage.
Did you use anti-static (ESD) precautions? Did you use a brush? Laptops are full of sensitive parts and it is not uncommon to zap something. I see your exact situation a lot when proper precautions are not taken.
A more likely scenario is that something is not properly connected or a connector or cable has been damaged.