Can you be a little more precise ? There are universal and PS3 bound flies, do you talk about non PS3 files ?! What exactly did you do till now (Used progskeet ? Valided dump ? Hash checked dumps ? Tried a jig ? and so on Give us some info)
Go to recovery mode, there it will ask for the firmware it's trying to complete. Find that firmware and put it on usb and try updating with it.
And like someone else said, it might be a loose cable for the blu-ray or wifi board. Don't take the sellers word that it's never been opened. Open it up and check for loose cables, before you try anything with a progskeet.