Power button not working on Lenovo z510 my fault

Recently I got a Lenovo z510 and I heard it had 1 free ram slot so I tried to open it… I taken all the screws from the bottom and push the keyboard out and then there were 2 tags I pulled the small thin one out but then scared and put it back and put all the screws back and I accidentally dropped the center screw and lost it and now my laptop won't turn on… It will only turn on when my charger is plugged in. When not charged the laptop is completely useless please help! I can't pay extra loans to fix my laptop

Do you have warranty? Maybe you can take it to the shop and they can do a free fix up for you

You should have taken it to the shop, now you'll have to let them repair the power button. The warranty was there for a reason and the hatch on the back for the RAM/WI-FI/Bluetooth was the ONLY thing to open, not the entire backing. You did the damage, and voided the warranty.