Please use the </> button or backticks (```) to format your post when it contains long snippets of code or configuration, as it's really hard to read otherwise 
You can check the previw window on the right when you write your post to see how it looks.
Please verify that the certificate has been exported correctly, share the output ( again , use the </> button or backticks ) of
cat /etc/kibana/elastic-ca.pem
ls -l /etc/kibana/elastic-ca.pem
openssl x509 -in elastic-ca.pem -text -noout
If the file (elastic-ca.pem) looks empty, please try to export it again using
openssl pkcs12 -in elastic-certificates.p12 -clcerts -nokeys -out elastic-ca.pem
(this is slightly different than the one I shared earlier , it contains -clcerts instead of -cacerts now ) and try again.