I have a Blade 180QX quadrotor / quadcopter and I had to move a red wire shoved under the circuit board when I fixed a broken power wire. Now the red wire shown out straight from the circuit board is not in the right configuration - or at least as it was. If I understood what it was for I might know how to place it. Is this a horizon sensor (temperature)? Ever since I had to move this wire, the quadrotor goes unstable when flying. The only appreciable change is the wire POSITION. The red wire was not attached anywhere else on the board. It was shoved under the circuit board inside the battery holder.
The red wire is the antenna. It can be seen sticking out of the board if you google for other images of "Blade 180QX board". It should only be connected at one end.
This thread recommends that you stick it out the side rather than putting it under the board, which is what would generally be the advice for antenna.
It might be that by repositioning it you have introduced some interference, but the new position should introduce less interference, so it's possible that something else is causing your unstability.
Whilst not wishing to detract from Rob's answer, and following on from Pete's suggestion of googling for other images, if you go to the manufacturer's website, Bladehelis, for that particular product, and look at the replacement parts link, you will see the controller board listed, the 5-in-1 Ctrl Unit, RX/ESC/Mix/Gyros/Ch6: 180 QX HD. On that page there is an image, albeit not a particularly good one, that clearly shows the red wire/antenna:
Without wishing to go into the mechanics of antennas (for this, take a look at How antenna radiates(how currents flows through wire)), it is sufficient to say that antennas only require to be connected to the PCB at one end, and so, you have not damaged your device, nor have you accidently disconnected the other end of the red wire, as it is meant to be "loose" anyway.
The manual, unfortunately, is of no help at all, with regards to this matter.
As an aside, if you want to have a look at a good blog about this copter, then take a look at Blade 180 QX HD Quadcopter Breakdown, on diysoup. There are plenty of photos of the PCB there, as well as a wealth of other information.
Do you have a picture of the other side of the board? Typically, when you have a broken wire like this, either (1) the wire pulls out of a cold solder joint and leaves a hole, or (2) the wire breaks and leaves a little piece of wire embedded in a (good) solder joint.
Given the fact that there is so little bare wire exposed, I think that you're in case (2), where I would bet the wire broke off at whatever joint in which it was originally soldered. If this is the case, you should see a little copper-colored bit sticking out of a solder blob or a via in the circuit board. I don't see this, or the hole from case (1), anywhere on the surface of the board you've shown, which, coupled with the fact that the other end of the wire being under the board, leads me to believe your problem point is on the bottom of the board.