[mothered]

from your words i understand that my item must have a warranty some where which is totally make sense as it's a brand new monitor , which leads to the following question :
how should i use the manufacturer's warranty to force the return ?

Contact the manufacturer directly and tell them about the defect, then say that Amazon Is refusing to accept your claim for a product that's well and truly covered by warranty.

There's no question that your monitor can be replaced/repaired, so don't allow the Idiocy of Amazon to tell you otherwise. The manufacturer will suggest the best course of action.