(Urgent) Can't turn on Maintenance Mode

Hello everyone, I am hoping someone is awake or at least able to see this post and help me.
I've read every post in here with the word "maintenance" in it, no luck.

I am trying turn ON the maintenance mode.

From Admin>Site Settings> Maintenance is set to Yes. I even checked from phpmyAdmin, under fanfiction_settings, maintenance is set to 1.

http://www.turkfanfiction.net/arsiv/

What could cause this? I am sure I used maintenance mode before, but it was years ago, I don't know what's wrong now.

I would really, really, appreciate if you could help me. We are moving to AO3 as a collection, I urgently need to close off the website. I'm a bit newbie with phpmyadmin, but I'll try my best to understand.

Thank you so much.