I had the same error, help resetting passwords, cashe and cookies.
Try may be it will help you

zes, me too. I have reset my password, then after a while became ok.

503 means, most of the time, that the cache system (varnish) didn’t manage to pass the request to the web server (apache). Or that there is a mixup somewhere with cookies, proxies and the browser cache. Clearing your browser should handle it, if not please let us know. The contact us form @ http://developer.qt.nokia.com/contact does not require a login.