My start button or a button wont work

Hello Nick, sorry about the horribly late response, you know how these sites are, sometimes you get a response within a day, sometimes in over 8 years...

For this I am assuming you have an original GBA or older, if this Gameboy is an SP or newer, I cant help you.

This is a relatively easy fix, the most common reason for this problem is that the conductive pads under the silicon pieces have become coated with... stuff? (I have no idea what the heck it is.)

> Take out the six screws on the back, two are under the batteries. They are usually tri-wing, but I have seen Original Gameboys have Phillips.

> The ribbon cable connects the two halves together. Be very cautious as if you tear this ribbon cable in any way, then congrats, you broke your screen. To remove on an original Gameboy ribbon cable, get a good grip on it and pull it out of its housing. If this is a Gameboy Pocket or newer, lift off the back shell. You will see the workings of the Gameboy. push up the two tabs on the sides of the ribbon cable, take out the three Philips screws, disconnect the ribbon cable and lift up the board.

> (Only follow this step if you have an original Gameboy) Take out the TEN (bit of an overkill there really...) Philips screws on the screen half of the board, and lift off the board. The screen is attached to this board, so be careful.

> Last step! remove the silicon piece of the button that is giving you trouble, and grab a piece of paper. Push the silicon piece and you should see the conductive pad stuck to the inside, take it and rub it on the paper, you should see a pencil-like mark appear on the paper. This cleans the pad. You can now reassemble the Gameboy and test it out.

My god that took ages to type...