Hi everyone, similar to my threads for OP3, OP3T, OP5 and OP5T, as only a few versions of unbrick tool are available here and that they allow to rollback to specific versions of Oxygen OS I decided to search for more and succeeded in that.
I linked to version 5.1.5 and 5.1.11 shared by @Fivegates and @Titokhan here and here.
Rest is provided by me.
As the instructions and Qualcomm drivers are already available here, I don't feel a need to rewrite them.
You can ask questions here on how to use and issues, however I might not be able to answer immediately.
Here are the files uploaded on AndroidFileHost ordered by Android version:
You can find a mirror for most versions here, courtesy of AnonymousWP.
Password for it is N3v3r S3ttl3 tm