Still a very, very confused newbie. I have done exactly what you have said. The unzipped file was given a name of "update" on Win 7 laptop sved on the usb stick. Device info screen shows
Andoid 7 onl7 no other details
Kernel 3.18.24
HMD-2.0.4 2017-07-05. 191425
Is this the correct update file or should it be 174159 instead of 191245.