The Nighthawk is definitely not what we would commonly call "V-shaped". Warm yes, definitely. V-shaped, not really.
It has bass/lower mids emphasis with a wide bump from 60 to 800 Hz (!), and then recessed upper mids/lower treble froom 800 to 4500 Hz.
I'm guessing you mean "less bass/lower mids emphasis".
I'm just surprised that you are putting so much effort/risk into modding them physically when you could achieve a better result by just EQing them.
I have owned my Nighthawk Carbon for almost 1 year now, and my Nighthawk Wood for almost 9 months.
None of them has ever stinked or smelled, not even slightly.
Your issue can't be normal, unfortunately. I hope you can have them checked somehow.