>>>The beneficiary, who is also the executor, turned up at a friends house and asked them to sign the will as witnesses
It's not the actual will which is witnessed but the signing of it. (The witnesses don't need to see the contents of the will or even to know that's what it is. They are simply witnessing that they saw the document being signed).
If the will wasn't signed (as your post states) then there can be no valid witnesses, since there was nothing for them to witness. Even if the will was signed by the testator, but the 'witnesses' didn't actually see it being signed, then nothing was witnessed.