Full health:

Hold 1 when Randar replaces your energy to fill all forty-seven bars.

Invincibility:

Collect all nineteen potions and herbs to become invincible after
your energy reaches zero. This will remain in effect until Randar,
Enni, or energy pellets are used to refill your life.

Sound test:

Hold Up/Left + 1 + 2 while Kelesis is walking towards the hole in
the opening sequence.