Login white page

Hi, I’m using wordpress with a childtheme and when i go to login page a blank page appears. This issue happens only with childtheme, not when I use the original theme. I have any problem with wp-login.php page and wp-admin but only with this login page (and registration page) when using childtheme: https://www.offrogratis.it/?ptype=login&page1=sign_in . I checked in childtheme’s functions.php for blank spaces but I’ve found any problem.
Ok, I can’t bump so what should I do to solve my problem? Give me a hand, please. I don’t ask you to spoon feed me but I’m desperate and I have no idea on how to get out of this issue. If you need more details ask me and I will provide them. Thank you