Days of Thunder [Model DMG-TH-USA]

Game genie:
00A?04F?E6E - Start a new game and select any game mode to get to players number selection screen, which is presumable should be started before the main menu selection. The code doesn't allow you to play the 1-player mode from there, but you still can run rather unfinished 2-player mode if use the link cable with two Game Boys. There are a lot of issues with this mode, some wrong positioned texts on the screen, you can't change the car color or player name. You able to select the course and play it somehow, but it mostly playable. The 4-player mode need some device, but even if you have it, you can't play this mode. It's quite in a basic state and working only as the 4-player hardware checking and players ready status display. The rest of the code doesn't connected even to this code at all, and has no any texts or screen layouts.