How to recover SSH access to EC2 instance?

Here are the steps to gain access:

1. Stop broken instance
2. Detach broken instance root volume
3. Start new instance that you can login to
4. Attach broken instance volume to new instance
5. Mount the broken instance volume at the OS level
6. Fix/undo the configuration on the broken instance volume
7. Unmount/detach broken (now-fixed) instance volume
8. Attach now-fixed volume to broken instance
9. Start broken (now-fixed) instance
10. Login