https://confluence.atlassian.com/jira064/upgrading-jira-using-a-rapid-upgrade-method-720411841.html

Software 7.1.8 -> 7.7.0
Core 7.1.8 -> 7.7.0

There seems self-installation package are downloadable, but in README, it says

BRIEF INSTALL GUIDE
-------------------

1. Install Oracle's (formerly Sun's) Java Development Kit (JDK) or
Java Runtime Environment (JRE) version 1.8 or above:

http://www.oracle.com/technetwork/java/javase/downloads/index.html

2. Set the JAVA_HOME variable to where you installed Java. The Windows
and Linux installers will do this for you. See the following instructions
for details:

http://docs.atlassian.com/jira/jadm-docs-077/Installing+Java

3. Set your JIRA Home Directory.
Instructions on how to set your JIRA Home Directory can be found here:

http://docs.atlassian.com/jira/jadm-docs-077/Setting+your+JIRA+application+h
ome+directory

4. Run 'bin\start-jira.bat' (for Windows) or 'bin/start-jira.sh' (for Linux/Sol
aris)
to start JIRA. Check that there are no errors on the console. See below for
troubleshooting advice.

5. Point your browser at http://localhost:8080/
You should see JIRA's Setup Wizard.

Full documentation is available online at:

http://docs.atlassian.com/jira/jadm-docs-077/Installing+JIRA+applications

upgraded.

if any issue found (in ~2wks), reopen this (or file a new ticket).