I head cannon the arch installation bandit as a girl.
Quaffing the potion of gender stability, now in your female form you strap on the head cannon and fire it at the arch installation bandit.
The arch bandit takes 5d7 damage and collapses prone. Seeing their leader defeated, the subordinate installation bandits flee. You have reclaimed Installation Cathedral from the bandits and can now invite the Installation Medium to summon the spirits of past operating systems.