If nothing seems to happen, check the likely sources of mismatch in a straightforward order. First confirm the platform and release: this instruction is for Genesis/Mega Drive, not SNES, Game Gear, or Master System. Next confirm the screen: it must be the story line screen, not the title screen or another menu. Then check that the input order was A, B, A, C, A, B, B, with each button pressed separately. Finally, verify that a controller remap has not swapped or omitted one of the game's three inputs.
If all of those points look correct and the result is still unclear, consult the original listing and the documentation for the specific hardware or emulator you are using. Do not compensate by adding random button holds, directions, repeated inputs, or alleged menu steps from an unrelated port. Keep notes about the version and setup if you want to compare results later. This guide is source-checked, not game-tested, so it cannot resolve every cartridge, regional, controller, or emulation edge case. A measured recheck is more useful than turning uncertainty into a confident but unsupported extra instruction.