How to unlock a firmware-locked Mac?
I have found one Mac computer in a E-waste container around 3 weeks ago, it's in a good state and it was with a charger. There were other devices but I was just interested in the Mac, so I took it with me when I try to turn it on it didn't turn on so I opened and cleaned it. Then it works it is lock firmware and has an user name with password, still no more info appears on the screen, isn't a new model but it's still a cute laptop. What can I do do unlock and start using it ? Will I have a trouble if I take it to any store ?
[Re-Titled by Moderator]