Suddenly rocketchat stopped working "502 gateway"

I was working with rocket chat for more than a year, using the snap version. suddenly for no reason it gave 502 error. checked the rocketchat-server status and showed:

May 12 22:00:33 ip-172-31-30-219 rocketchat-server.rocketchat-server[3258]: Mongo is not available, can't st

I read in some posts that it could be due to inproper rocketchat update due to skipping multiple mongo versions (i don’t have another mongo on same server) and tried to

snap revert rocketchat-server

Now the mongo is up but rocket chat is just loaded and not active for no reason:
● snap.rocketchat-server.rocketchat-server.service - Service for snap application rocketchat-server.rocketchat-server
Loaded: loaded (/etc/systemd/system/snap.rocketchat-server.rocketchat-server.service; enabled; vendor preset: enabled)
Active: inactive (dead) since Tue 2020-05-12 22:24:18 UTC; 5s ago
Process: 6173 ExecStart=/usr/bin/snap run rocketchat-server (code=exited, status=0/SUCCESS)
Main PID: 6173 (code=exited, status=0/SUCCESS)

May 12 22:24:18 ip-172-31-30-219 systemd[1]: Started Service for snap application rocketchat-server.rocketchat-server.

Any help please. or a way to backup the data to restore it on a new server?