Laptop doesn't turn on

Hello, a friend of mine gave me a laptop which had a cooling problem. Actually before she gave it to me she gave it to a specialist who said that there is a problem with the heatsink and we had to replace it. But he asked for a lot of money, so we decided to buy one ourselves and make the replace. She also damaged the AC adapter so we couldn't turn it on at all. Anyway we bought a new heatsink(exactly the same as the old one) and I did the replace. We also took an AC adapter from another laptop to try it. But the laptop doesn't turn on at all. I double-checked all the cables and the screws, i'm pretty sure i did everything correctly.
The leds are like this:
Plug = green
Power icon = blank (hence why it doesn't turn on)
Battery = orange
Hard drive = blank

It seems the adapter is working and the battery is loading but when i press the power button nothing happens. Any advice?

Laptop = Toshiba Satellite L300-14P

 

Check the label on the adapter and make sure it is putting out the same voltage and at least the same amperage or more.

 

Hi,

input voltage : 100-240V
output voltage : 19V
output current : 4.74A / 90W

I believe the adapter is ok. Any other idea?

 

What was the rating of the old adapter?

 

I'm not the expert on these things but considering the leds turn on when I connect the adapter and the battery seems to loading makes me not believe that there is something wrong with the adapter or the plug.

I'm pretty sure I made something wrong when I opened the case to replace the heatsink, but I don't know what it could be?
Could I replace the heatsink wrong, would a laptop with no heatsink turn on at all? or it doesn't matter? Is it possible I burned the motherboard or something by touching it with my hands?

Anyways I'm going for one last try, I'll remove everything again and put it together one more time carefully in case some wire is loose or whatever.