If the settings are too confusing, it is always possible to do a full reset of the calculator by pushing an unfolded paper clip into the RESET hole at the back of the calculator. The calculator is reset but the contents of memory are retained, only the stack is cleared.
Alternatively, you could perform a reset - Press and hold the top left and right keys then the [ON] button, the 50g beeps and asks whether the user wants to try to recover the contents of memory. Press any key once and followed by answering NO to this question means that the calculator will be completely reset and everything will be deleted, bringing the calculator back to its state as new.
Another method is to remove all the batteries (4 AA batteries and the CR2032 cell) for about 15 minutes. Replace the batteries, the 50g will boot up. The 50g system clock would reset to factory default setting of 12/30/02.