Perhaps ask a more specific question? The OP asked what "Fire Maringo" was about - not the meaning of the word "maringo".

The shanty, as explained here and in other threads, is about screwing cotton.

Hugill, as I said earlier, seemed to think "maringo" is an Irish word, which he says in Shanties of the Seven Seas is found in many Irish folksongs, where he quotes:

As I was a going along the road
As I was a going a-walking
I heard a young lassie in the shade
To a young man she was talking
Ch With a maringo do-a-day
With a maringo do-a-daddy-o!

Whilst I can't say I've noticed the word cropping up in other Irish songs, if Hugill was correct it seems to be one of those nonsense words which may or may not be derived from the Irish language, or may simply be a bit of "mouth music" to fill in a chorus.

That doesn't explain the expression "Fire maringo". It could have been an expression from another language, perhaps a non-English shanty, which got picked up because the singer liked it. After all, it's a good line to belt out - it doesn't have to mean anything. Perhaps Doerflinger was right, and it came from the black stevedores the British cotton screwers worked alongside.