Laptop will not power on

I replace the screen and everything was working fine. I noticed the track pad was a little sticky so I powered down and had to remove the internal battery to fix the track pad. Once I reassembled everything it is totally dead. No lights even when the charger is connected. I have taken it back apart and check for any loose connections. I have removed and reseated the RAM. I have tried to run off of ac power only with the battery removed but it is still completely dead. I have also tried a har reset with the battery out pressing the power button for 60 seconds and then going back and trying it all again.