If the computer will not power up with battery or external power you will have to tear the unit down and take the drive out of the machine and then take the top off and then remove the disk. If you can get power to it, attach a usb mouse and hold down the right side button when you put power on it and if it can it will push out the disk. Also on some the of the drives there use to be a push button just inside the left or right side of the drive and with power it would activate the eject sequence. But it also requires power.
Good luck