I have a Macbook Pro 17' (A1229) and it is clicking when I hold the power button down... Whats wrong?

I have a Macbook Pro 17' (A1229) and I replaced the screen. It worked. Now today I tried turning it back on and nothing. It will not even boot up. When I try to power it up all I hear is a faint clicking from inside. I fear she may be dead. All the connections look fine and I have made sure they were all properly secured, even my battery still charges but it still wont turn on. Nothing happens besides the faint clicking... Any advice?