Board Thread:Questions?/@comment-29552407-20160809115123

When I first was using my Gameboy after about 20 years, the top screen fell off due to old glue. However, when it fell off, I noticed a 'B' handwritten on the bottom left corner of the area underneath the top screen. I don't know what this means, so I'm asking the forum to maybe find an answer. I will attach a picture so you can see for yourself. 