The only ideas I’ve left is to re-check project settings – both here and at Github – for anything nondefault-looking or that may put undue strain on the CI. Also reset Travis integration according to Pushes won't trigger new builds anymore after the project has been inactive for a long time.
And after that, try building old commits that built successfully before (you’ll need to create branches at them for that).
If that doen’t help then you can be sure you are just banned. Since you’ve been ignoring abuse reports for so long, I reckon that’s possible.