I'm at the end of my phd's 4th year in molecular biology.

If a couple more in vivo experiments don't produce the results we expect then most of the data i've generated in another model is useless.

For some reason my advisor decided to explore mechanism based on a phenotype in 1 model, now it's potentially useless if we can't see the same phenotype in other models. It'll likely take me till the end of my 5th year to assess these other models.

I thought the normal procedure was to validate a hypothesis in multiple models to make sure it's not an artifact, then explore mechanism. For some reason we didn't follow this strategy and I didn't realize how risky the hole we were digging until too late.

I've learned a lot during my phd and my advisor is actually a great mentor but they basically refuse any accountability on how this project has gone. I wanted to go into biotech after my phd but now I doubt I'll be competitive for even mediocre academia positions if this don't go well. I have enough data to publish in some borderline predatory journal even now, but without a phenotype the data is about as unimpactful as you can get while still being publishable.

I don't know what to do. Should I just accept my losses and hope for the best in postdoc interviews? Spend another 3 years for a new project that also has a good likelihood to not work?