couple of things.
1. When u switch it on do u get red light on reset button and then when u hit reset does it go green?
2. When u turn on does the fan still come on?
3. When on does the tray still eject?
4. If the tray ejects can u put a disc in and does it spin ( listen for drive motor whirring)
I would initially suspect that it aint put back together right.
If this is first time you've had it apart then it could be a case of a connector not quite pushed back in far enough.
As there was a jam though it could also be a blown fuse. There r a lot of surface mount fuses on the motherboard and one of these might have blown.
Fuse guide is
HERE!!
Good luck.