Rohga Armor Force SHMUP

[ReyVGM]

Does anyone know how to get the different endings for this arcade game?
I noticed there is a cheat to skip levels and it also jumps you to 4 different endings, problem is I tried beating the game level by level, I tried selecting any of the 4 machines, tried beating without continuing, dying a lot, continuing a lot, 1 player, 2 players, etc, etc and I still get the same ending.
Any of you know what needs to be done to achieve the other ones?

[Malroth]

What about scoring or rank? Maybe having a huge score with the highest rank possible will get a better ending.

[ReyVGM]

Nope. The other endings seem to be 'bad' endings. It even seems as if the last level was a different one altogether judging from the "escape" images in the other endings.
The game has no branching paths and there is no way to let yourself lose or let a boss espape to get a bad ending.

I guess those endings are stuff left in by the programmers and weren't used considering that the standard ending I get varies if I use 1 or 2 players yet the other 3 endings don't change at all, even if I just enable the 2nd player; which is a female.