As you surmised, it was in Final Night that the tragic even happened in. Hal gave his life to save the world and sacrificed himself to reignite the sun and destroy the sun eatter.
ok its like this the sun eater trys to eat the sun which than causes the earth to freeze green lantern then realises that hal is the only one who could save the planet so he gets hal to help them hal then flies into space starts reciting the gl oath summens all his power and reignites the sun destroys the sun eater and blows himself up in the process this then brings us into day of judgement where hal is brouht back to life as the spectre