NO WAY !!
if there was a way to check if pin valid then there will be no need to put a cam or pinpad to get pin, because it will be easy to bruteforce the pin in less 3 minutes.
Everytime i want to enter this page showthread.php?t=45800&page=10
i see a popup that ask for username and pass
I think its a persistant xss injected in this page