cant 100% chapter 9

[QUEEK YESYES]

i cant 100% chapter 9 cause i killed the boss that gives the health upgrade but didnt pull the lever behind him too get the checkpoint cause wanted to explore more but died and it re-spawned me before the fight and now when i kill him it dosnt give me the health upgrade and i dont have it cause ive looked for videos for help too see if i missed a boss and i can see my hp dosnt match up. any idea?

[Pablo Escobark]

skill issue