The reason you got a hermi was stress from high heat and lack of air exchange. " No extractor fans are installed. The box stays at a temperature just above room temp (mid 20 degrees C); it doesn't need one." That's not the only reason we use extractors.
Go for something beefier than a computer fan next time- a 4" duct booster plus a passive intake would be more appropriate for that size container.
Lose the tinfoil.
And I was amused to see your opinion of p4b's log.