After navigating through the Chōzōru Ruins and infiltrating the Space Pirate mothership, you'll eventually reach a large chamber. This chamber contains ancient Chozo technology. You'll need to activate a series of switches or solve a small puzzle to fully power up the Chozo statue. Once activated, the statue will reveal a hidden compartment containing a new, upgraded Power Suit.
Upon acquiring this new Power Suit, Samus will regain all her previous abilities (Missiles, Bombs, Varia Suit, etc.) and gain some additional enhancements. This marks the end of the Zero Suit segment and the return to full power. With your Power Suit restored, you can now confront the Space Pirates directly and escape the mothership. This new suit is more powerful than your previous one, preparing you for the final confrontation.