some info about the sandbox needed

I’ve got a device
it needs a firmware upgrade
the page containing the file is reported by Firefox as an “Unwanted Software Page!”.(i heard that also by chrome)
the file itself is apparently flagged by some anti viruses programs.
the company itself says not to wory and that it’s a false positive.
so i was thinking of downloading the file and run it in the sandbox;
-will this keep me safe?
-will it still be able to do the upgrade to the device?
-should i also run Firefox in the sandbox while downloading this file?
i’m also worried that after the device gets upgraded, it might send stuff to my pc through the usb cable.
(it’s an E-cigarette mod)

To answer your question of will it keep you safe? Yes. Will it be able to update the device? Maybe though I doubt it will have the access needed but you can try.