Complex sentence: Hácha remained as technical head of state with the title of State President, but Germany rendered him all but powerless, vesting real power in the Reichsprotektor, who served as Hitler's personal representative.
Split into simpler sentences: Hácha remained as technical head of state with the title of State President, but was rendered all but powerless. Real power was vested in the Reichsprotektor, who served as Hitler's personal representative.