At the title screen, hold Select and press Start. The Datacheck allows you to manage your saved files.
PRG Bankswitching Test
Press and hold Select on the first controller and Select + Start on the second controller at the same time, then press Reset. The game will perform a quick PRG bankswitching test, and 8-bit summing for first and last bytes of every PRG bank. If passed, then the game will continue normal operation. If fails, then the screen will turn white and game hangs.