What to look for when buying a Game Boy Colour

Not sure if this is the right place for this or not but, Im looking to buy a Game Boy Colour to relive my child hood and play some Pokemon games (Blue, red and yellow). Im wondering what I should look out for when buying one, are there any marks of authenticity that I should look out for, any fake or refurbished marks, how can I tell if its in good condition or a good quality refurb etc?

In my experience, since I bought an old used Nintendo Gameboy Classic (the brick version), there are two things to consider when buying a Gameboy.

No. 1 Does the battery compartment still work and conduct power while playing?

No. 2 Are there any loose contacts or damaged cables/components inside the case?

No.3 Of course, the overall condition of the device should also be suitable for playing, but that's obvious.

You should ask to try the device before purchasing it so that you can check for possible damage.

In order to check the first problem, namely whether the battery compartment is still intact, you should insert batteries into the compartment and try to switch on the Gameboy. Try rotating the batteries inside the compartment while the unit is turned on. If it stays on and does not reset when rotated, it should be fine. Spilled battery acid can attack the contacts and sometimes cause the current to not flow properly.

The second problem will also be noticed quite quickly while playing, so insert a game and try to play it. Loose contacts or faulty hardware should be noticed pretty quickly because the game isn't displayed correctly, the Gameboy is constantly reset, or the screen displays nothing at all. You can try to shake the Gameboy a little. These devices are designed to withstand a few blows. In this way the device is not damaged and loose contacts are obvious at the latest then. But make sure it's not a user error because the game isn't inserted the right way. But if you've played with a Gameboy before, you'll know when it's been inserted correctly because it won't move freely.

So, in summary, just be prepared when testing a Gameboy before you buy it. Bring a fresh pair of batteries and a game you can rely on to work. (Old games like Pokemon may no longer be able to save because the internal battery is empty, but they are still playable).