Unable to start ES 7.3.1 after configuring internode communication encryption

is self explanatory.

is wrong, it should be

xpack.security.transport.ssl.truststore.path: /etc/elasticsearch/certs/node-1.p12

How ? What was the setting name ? Can you share the output of

bin/elasticsearch-keystore list

?

You can verify the password outside of elasticsearch running

openssl pkcs12 -in /etc/elasticsearch/certs/node-1.p12

it will prompt you for the password, so you can try and see if it is the password you think it is.