I've sent them email this morning (it's 11:35PM in my country right now), but still got no reply. I don't know whom to call on the telephone here in my country.
What baffles me completely is the absence of any sensible error message. For example, when I try to upload some other type of file (like .txt), I do get the full "file incorrect", or something like that, error.
The other thing that really grinds my gears is that when I click the "Check Now" button, next to the "Check Online Now for Latest Firmware Version" label, I get the lovely "connection error !" message (exact full quote).
The only clue I found is in the URL (in the screenshot), where it says: "ERR_REQ_TOO_LONG". I don't know what this means exactly. I don't think it's "Request Too Long", because this error page pops up almost instantly after I click the "Upload" button.
I don't think I'll spend much more time and energy on this, unless I hear from the Support soon.