The WPA family of Powerline Kits come with a wireless unit which is intended to be the remote or downstream unit and a non-wireless unit which is intended to be the upstream unit and connected to the router.
The kits in general appear to be named after the wireless device (numerically). The non wifi device is another model number of similar performance (ie AV1000, AV1200 or AV2000) which is generally available in a matching pair under that number
The web page for the KIT makes no reference to the upstream (router connected) component and the firmware available on the KIT page is not applicable to the non-wired component. Specifically the WIFI devices seem to have BIN files and the standard powerline GGL files.
It is not clear if one should be updating the standard powerline device based upon the model number and version located on the back of if the KIT devices are somehow "Married" and managed as a couple.
In my case I have a TL-WPA7510 KIT V1 which includes a WPA7510 V1 and a PA7010 V2. I have tried to update the PA7010 V2 from the TL-PA7010 V2 Support page, but the upgrade fails. So not clear if I am or am not doing this correctly.
I think this should be clarified on the Kit page and in the manual. The manual for my 7510 kit (section 3.11.3) only covers updating the firmware from the wireless control panel, which I assume is for the WPA device only.