"Bonnanj mwen chavire" Is bonnanj good spirit? and why say CHAVIRE?

bonnanj, here, could mean "good sense".
bonnanj - spirit
chavire → knocked over, turned upside down (like a car)

Bonnanj mwen chavire (expression)
My good sense is gone.
My sanity is gone.

Some synonymous Creole expressions are:
Bonnanj mwen pati
Lòlòj mwen chavire
Mwen pèdi tout bon sans
Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words