NETGEAR genie Requires an .img file to Upgrade Firmware

I want to upgrade the firmware on my WN300RP WiFi range extender. When I connect to my range extender using mywifi,net (NETGEAR Genie) and go into Maintenance - Firmware Upgrade I can see I'm running version V1.0.1.24. I next tried to "Check for New Version from the Internet" which responded by saying "No New Firmware Available". But, according to the Netgear download center, the current version is V1.0.2.64. So, I decided to try the upgrade manually. I easily download the V1.0.2.64 zip file and extracted it into a folder on my Windows 10 computer. The name of the extracted file is WN3000RP-V1.0.2.64_1.1.86.chk. When I attempt to upload this file I receive the message "Please assign the correct file. (The file format is "*.img")".  So, I renamed the file to WN3000RP-V1.0.2.64_1.1.86.img and tried again. I was then told that the file for the firwware upgrade is incorrect. I then checked all the other newer firmware versions and they all only provide a file with a .chk extension.

Is there an .img file available to upgrade the firmware for this range extender? Or, is there a way to have the NETGEAR Genie accept a .chk file? If it matters, the browser I'm using is Google Chrome.

Thank you in advance for your help!

Dannyberg