Sometimes you bump into a piece of software that shows real promise but ... it is dead. Defunct. b2evolution is one such software. If you have the programming chops you could roll up your sleeves and get to work:

• fixing its bugs.
• making it compatible with the latest PHP versions.
• cleaning up its UI.
• adding/removing some of its features.
• fixing its UX (user experience) problems
• bumping up its database versions.
• reorganizing its code.
• doing some refactoring perhaps to improve its speed or fix some "code smells".
• fixing the documentation etc.

What you are really doing at this point is trying to breathe life back into a software project. Not an easy task if you ask me especially if there are better alternatives to it. b2evolution needs just that at this moment. May be someone some day will fork it on Github and continue its development.