Now we have to rely on hackers to figure out what is the upgrade process or if you want to get your hands dirty(If you know some soldering) then buy ch341a programmer and directly flash the firmware onto the chip
Note :- I think, there is not a single file in the firmware upgrade zip package...
put the zip file in a sd card and insert it into the camera , power on the camera while holding the reset button. If it does'nt work then We have to analyze the firmware upgrade mechanism after reverse engineering the firmware file.( I encountered the same problem so I atleast got the firmware...