ASAP Prenumbra requiem missing fuse i need to finish game

[Ashtoreth]

(...) collected a fuse I went through a hidden vent and died, when it loaded I no longer had the fuse (...)

Sorry if I misunderstood you, but do you mean you were carrying the fuse with you inside the vent?
If not, where exactly did you place the fuse before entering the vent?

Anyway, if you died electrocuted in the second puddle of water, the fuse should be either back inside the box or wherever you left it.