520 Bad Gateway Error only on ssl

I have a website working on Cloudflare’s ssl and now I added another one but it seems this didn’t work because, when I try to get in to my site using ssl, I couldn’t connect but when I do try to connect without ssl I can. It is giving 520 gateway error. How can I find the error. My working site is nenerede.co. Not working site is firminf.com

The 520 error is essentially a “catch-all” response for when the origin server returns something unexpected or something that is not tolerated/interpreted (protocol violation or empty response).

https://support.cloudflare.com/hc/en-us/articles/200171936-Error-520-Web-server-is-returning-an-unknown-error