Sadly the original hardware is slowly degrading over time. Nintendo DS lite screens for example are all yellowing at this age. Buttons suffer too, my gameboy color is just a paperweight now because the buttons hardly register a press. Maybe these issues can be repaired but I’m not skilled with a soldering iron which is a big requirement it seems.
I run a video games business and fix button issues all the time!
All you'll need to do to fix a GBC with stuff buttons is open it up (requires a tri wing screwdriver, $2 from eBay), clean the button pads with a q-tip and alcohol.
The pads in question are the black bits on the back of the rubber immediately underneath the button, as well as the circular copper traces on the board that the black bits come into contact with when you depress the button.
You might need 3 or 4 q-tips. You'll know when you're done because the q-tips will stop turning black.
Takes 10 minutes overall and is only slightly more technical than wiping your arse! Don't be intimidated!
I bought a no solder IPS screen for gameboy color. Think I bought the kit off eBay, it came with a new case and buttons too. It's pretty great! (And if I can do it anyone can)
The GBC is quite easy to disassemble (If you have one of Nintendo's silly triwing screwdrivers). Give the pads under the buttons a rub with some isopropyl, and at an extreme buy some new conductive silicone pads for about £8 online.
No soldering required to get you back up and running.
It's relatively easy to learn soldering basics, and even if you're not good at soldering, it's pretty forgiving (especially on older hardware where the components aren't so finicky).
For what it’s worth, I’ve managed to successfully mod a Game Boy Advance as a total soldering noob, with a cheap poor quality iron from Amazon. Some mods (particularly for home consoles) are difficult as all hell if you’re inexperienced, but the Game Boy tends to be fairly easy-going. There’s also an increasing number of mods (particularly screens) that are slightly more expensive, but are solder-less (or solder optional). Macho Nacho on YouTube covers quite a few of them.
As for your buttons, you can buy new rubber membranes that make contact with the board to register the press. Give the board a good clean with isopropyl and pop some new membranes in and your buttons will no doubt be good as new—no soldering needed!
I used to suck with a soldering iron, but if it's something that interests you, just give it a shot.
If you're deathly afraid of making mistakes, get a desoldering iron. If you mess up just suck the solder up, reapply a bit of flux as necessary, and try again.
