On the Phantom FCP40 (essentially a Phantom 1), the GPS cable connects directly to the Naza controller box, not to the board as shown here. Also the compass (magnetometer) is connected to the main board, not the GPS unit in the top shell, so you don't need to remove it to remove the top shell.
It's common to improve GPS performance on Phantoms by putting additional shielding over the GPS antenna, rerouting the GPS cable so that it goes behind the shielding instead of in front of it, and putting extra shielding around the cable itself. Some also replace the ceramic antenna with a better one. This is especially true of the Phantom 2 which has an internal wifi transmitter mounted just under the GPS antenna. There are plenty of videos on Youtube about doing this.
I found that it's entirely possible to remove the optical drive without removing the whole subframe. You can remove the four screws on the sides of the drive quite easily, remove the other end of the audio cable then unscrew the two screws on the back of the drive holding the interconnect board to the drive (the only fiddly bit as it's hard to get a a good angle onto those two screws), then gently lift the front of the drive and pull it forward.
For all those poor people who have wrecked their Minis by following the bad advice on this page, I fixed mine by replacing this part:
http://www.powerbookmedic.com/Mac-Mini-I... (Apple part no 922-8807).
I did manage to solder a connector back onto the visible contacts on my original board, but it didn't work; the replacement worked fine.
If your cable is damaged too, you'll need to replace that too, but note that there are several different ones, and SKU17434 (Apple part 922-7319) is NOT compatible with the above board. I don't know the exact model of cable - having received the wrong one I managed to repair my original one.