Restoring a Broken $2 Tetris Handheld. 9999999 Games in 1 --- AF invention

I bought this old broken Tetris style brick game hand held console for restoration for $2. You can also buy similar devices new for the same price, but sometimes it's about the journey, not the destination. I don't know what math they used to calculate the promised 9999999 games, but I think the real number is a bit under 3000, mostly different variation of Tetris. The console is badly yellowed and dirty, the audio doesn't work, some screws are missing, and there is a lot of rust on the contacts.