well then you can read up on here and see what you want to do
switch goes into a 10 ohm resistor on top of board then drops under the motherboard then back on top as shown in the pic.
then ends up going to the southbridge then ends up on the dvd power plug (pin 2) as pin 1 is empty
looking at the top pic
right side of the resistor (R1G3) yo can check for conductivity to pin 2 on the dvd power connector.
this is with the switch left alone (not pressed)...
left side of the resistor(R1G3) to pin 2 on dvd power connector should show 10 ohms when the switch is pressed in.
(mine shown 9.95 close enough)

so bottom line after checking this is either that 10ohm resistor (R1G3) is blown or it's the sense control within the southchip
which brings you to this post...
this is if you checked everything along the way of the eject button...
so start reading....
DVD eject problem or bottom line is,
you have a good choice to buy a southbridge chip and have it re-balled and heated back on after removable of the failed one to