A Few Days After JencoMart Migrates the User Credentials Database

A few days after JencoMart migrates the user credentials database to Google Cloud Platform and shuts down the old server, the new database server stops responding to SSH connections. It is still serving database requests to the application servers correctly. What three steps should you take to diagnose the problem? (Choose three.)

A) Delete the virtual machine (VM) and disks and create a new one
B) Delete the instance, attach the disk to a new VM, and investigate
C) Take a snapshot of the disk and connect to a new machine to investigate
D) Check inbound firewall rules for the network the machine is connected to
E) Connect the machine to another network with very simple firewall rules and investigate
F) Print the Serial Console output for the instance for troubleshooting, activate the interactive console, and investigate