GB Micro, released in 2005, is amazing example of miniaturisation with it's paper-thin (literally, it's about 0.4 mm thick) multi-layered PCBs and flex cables going in between those layers, without any connectors, to save space. It's something to look at in awe. Or horror, If you broke something inside.
As you can see, I broke ribbon cable, connecting START/SELECT board to motherboard - it's pretty easy to do when you are taking off metal shielding or pulling out motherboard not gently enough. Not willing to throw out $50 into dumpster, I decided to snoop around the motherboard to find if there any way to fix this mess.
1) Magnifying glass (you won't get anywhere without it)
2) Soldering iron with fine tip
3) Thinnest wire you could get (I'm using 0.5 sq.mm), preferably in teflon isolation, about 30 cm
4) Scalpel or cardboard knife
5) (Optional) Some heat shrink tube (6-7 mm diameter, I think)
Step 1: Solder Wires to START/SELECT Board
Use scalpel or knife to remove green solder mask from soldering pads - be very careful not to remove pads themselves, apply very little pressure. Cut wires into 5-6 cm pieces and solder them to the points as shown in picture. Don't worry abou them being to long - there is anough space between screen and motherboard to fit them. After that, flip the board (make sure that wider notch in the middle of the board is facing towards you and wires are away from you) and carefully bend all wires at the top of the board, so they go under it (check pictures on the next page).
Step 2: Solder to Motherboard
Prepare soldering pads, like in previous step and solder wires according to instruction on the first picture.
After that you can fasten wires to motherboard using small piece of heat-shrink tube.
As I said, you won't get far without magnifying glass - that part of PCB where all solder pads are located ia about 7 mm wide. Also on the third pic you can see how I messed up wiring for START and SELECT.
...I actually got it right only on the third try. So check how it works before assembling unit. You might also need to slightly modify your housing to fit START/SELECT board with wires.
Now to the part on how I found out where to solder to. On the slide number 4 you can see tool I used - it's two needles with resistor inbetween. I had a hunch that flex cable connection will have some vias on PCB, so I probed all suspicious connections with this tool on powered on console, looking at it's reaction. It's also is surefire way to burn your console, even with resistor in there to prevent short-circuits, so please don't do it this way unless you either know what you are doing or you're doing it on something already considered broken. And never do it with something powered by mains - that way in addition to burning console you might also set your house on fire or kill yourself.
Step 3: Look at Him Go
Well, now you have working GB Micro. And probably, oath to yourself to NEVER EVER open it again.