Website config troubleshooting


I am trying to reconfigure my website because I recently switched to https and it seems that my former config does not work any longer...
After many attempts, I finally deleted all wpmudev plugins from my website to start the installation process from scratch.
I've also tried to delete my website from the My website section but only got a "502 Bad Gateway" error.
Now, whenever I try to access the My website section, I'm always getting the same "502 Bad Gateway" error ...

Your help would be highly appreciated in this matter.

Thank you,

Mikael Hakmi