Galera stopped working after reboot

I was testing Galera and it seemed to work initially. But after that when I configured keepalived, everything messed up and I had to restore an image backup I had taken before installing keepalived.

But galera isn't working still.

Since I am still experimenting, the data wasn't important.

So I cleared the contents of the datadir for mysql and copied over an old copy (taken before initially configuring galera) I had made in another directory.

I did the same for my 2 nodes - SG01 & SG02

I then configured galera on both SG01 & SG02.

Current firewall config on both environments:

forge@sg01-mllmconcepts-com:~$ sudo ufw show added
Added user rules (see 'ufw status' for running firewall):
ufw allow 22
ufw allow 80
ufw allow 443
ufw allow from 192.168.a.b
ufw allow from 192.168.c.d
ufw allow 4567/udp
ufw allow 3306,4444,4567,4568/tcp
root@sg01-mllmconcepts-com:~# 

root@sg02-mllmconcepts-com:~# sudo ufw show added
Added user rules (see 'ufw status' for running firewall):
ufw allow 22
ufw allow 80
ufw allow 443
ufw allow from 192.168.a.b
ufw allow from 192.168.c.d
ufw allow 3306,4444,4567,4568/tcp
ufw allow 4567/udp
root@sg02-mllmconcepts-com:~# 

SG02 Config:

[mysqld]
binlog_format=ROW
default-storage-engine=innodb
innodb_autoinc_lock_mode=2
bind-address=0.0.0.0

# Galera Provider Configuration
wsrep_on=ON
wsrep_provider=/usr/lib/galera/libgalera_smm.so

# Galera Cluster Configuration
wsrep_cluster_name="mllm_cluster"
wsrep_cluster_address="gcomm://192.168.a.b,192.168.c.d"

# Galera Synchronization Configuration
wsrep_sst_method=rsync

# Galera Node Configuration
wsrep_node_address="192.168.c.d"
wsrep_node_name="SG02"

SG01 Config

[mysqld]
binlog_format=ROW
default-storage-engine=innodb
innodb_autoinc_lock_mode=2
bind-address=0.0.0.0

# Galera Provider Configuration
wsrep_on=ON
wsrep_provider=/usr/lib/galera/libgalera_smm.so

# Galera Cluster Configuration
wsrep_cluster_name="mllm_cluster"
wsrep_cluster_address="gcomm://192.168.a.b,192.168.c.d"

# Galera Synchronization Configuration
wsrep_sst_method=rsync

# Galera Node Configuration
wsrep_node_address="192.168.a.b"
wsrep_node_name="SG01"

Then I brought up SG02 (master) using sudo galera_new_cluster and it worked.

root@sg02-mllmconcepts-com:~# mysql -u root  -e "SHOW STATUS LIKE 'wsrep_cluster_size'"
+--------------------+-------+
| Variable_name      | Value |
+--------------------+-------+
| wsrep_cluster_size | 1     |
+--------------------+-------+
root@sg02-mllmconcepts-com:~# 

But when I try bringing up SG01, it doesn't work:

forge@sg01-mllmconcepts-com:~$ sudo systemctl start mysql
Job for mariadb.service failed because the control process exited with error code.
See "systemctl status mariadb.service" and "journalctl -xe" for details.
forge@sg01-mllmconcepts-com:~$ 

Status and Journalctl isn't helping me much :(

forge@sg01-mllmconcepts-com:~$ systemctl status mariadb.service
● mariadb.service - MariaDB 10.3.21 database server
   Loaded: loaded (/lib/systemd/system/mariadb.service; enabled; vendor preset: enabled)
  Drop-In: /etc/systemd/system/mariadb.service.d
           └─migrated-from-my.cnf-settings.conf
   Active: failed (Result: exit-code) since Thu 2020-01-09 07:32:29 IST; 42s ago
     Docs: man:mysqld(8)
           https://mariadb.com/kb/en/library/systemd/
  Process: 10999 ExecStartPost=/etc/mysql/debian-start (code=exited, status=0/SUCCESS)
  Process: 10997 ExecStartPost=/bin/sh -c systemctl unset-environment _WSREP_START_POSITION (code=exited, status=0/SUCCESS)
  Process: 11624 ExecStart=/usr/sbin/mysqld $MYSQLD_OPTS $_WSREP_NEW_CLUSTER $_WSREP_START_POSITION (code=exited, status=1/FAILURE)
  Process: 11405 ExecStartPre=/bin/sh -c [ ! -e /usr/bin/galera_recovery ] && VAR= ||   VAR=`/usr/bin/galera_recovery`; [ $? -eq 0 ]   && systemctl set-envir
  Process: 11403 ExecStartPre=/bin/sh -c systemctl unset-environment _WSREP_START_POSITION (code=exited, status=0/SUCCESS)
  Process: 11392 ExecStartPre=/usr/bin/install -m 755 -o mysql -g root -d /var/run/mysqld (code=exited, status=0/SUCCESS)
 Main PID: 11624 (code=exited, status=1/FAILURE)
   Status: "MariaDB server is down"

Any help appreciated. Thanks in advance.

It works if I delete the Galera config for SG01 and start mysql. But I really need it to be part of Galera cluster.