As this is normal thing in this world for every DVD players and most of them they think that the ejector grip had broken or damaged but did you observed if their is a cd or dvd then it can open easily.This is because of magnet which is above the spindle.I have an lg dvd rom which also had the same problem but ocasionaly it works whenever i removed from pc and again attached to it since this shows that somewhere it is loosened or have something problem.I will describe how to fix this.
First Remove optical drive from PC and keep it on seperate table soit will beeasier to  open any screws or anything just follow my steps.Turn back you see a label of sticker and remove this so you can find how to remove the next thing.Their is a cover plate which can be removed by using knife or scissors.no need to use pressure just using sharp knife prying over the cover plate to glue it.Cmon you have to open carefully this things so again have close the cover plate.

Rotate the small metal plate in clock wise direction to remove the plastic puckIf you look into deeper their you find small lid and unscrew it.As the lid is removed you will find a small magnet which is attached to spindle Check the magnet strength by placing a screw driver or knife.If the magnet strength is too much then it is the reason for ejecting even when button is pressed for ejecting the tray.
For this thing take a duct tape and cut into circular shape as the plastic cover plate has I may think it is around 10mm and place this tape on that 10mm also make a hole in center of this duct tape so that the spindle will be purely fit.Now close with the plastic and then use the cover plate to close totally.place it in your computer and you will stun as it is working.