Well based on what I understand from the team, they say they have not installed any new plugins or themes; moreover the site was functioning normally until it was noticed that it was down.
Once I got to know, I tried couple of debugging and fixes that was suggested in your documentation, but none of those worked. I also tried to reset the Ip / domain to point to the machine IP rather than a static in anticipation that this might work...but it didn't.
Apart from that, I had tried to remove the bitnami banner too.
Other that none, I believe.