I’d open the box and compare the two and keep the one I like.I just received the replacement unit, but still deciding if I will keep my own phone and live with the problems, or accept the replacement unit. I didn't open it yet, so I don't know if the model number will start with N or F. For sure it won't start with M.
If it was you, would you rather live with your phone that is having problem, or accept a replacement unit?