@dusty_nv you may want to have a look at this.
It looks like the script you refer to might need to be updated. Try downloading 1.5 from here for the latest JetPack:
To be honest I don’t know a lot about PyTorch, but my understanding is 1.5 is for the latest JetPack with CUDA 10.2
Do you need a specific version? If so it might be worth it to reflash with 4.3, and only upgrade when the thing you need is ready for 4.4. Upgrading should work without a problem, but downgrading… Well it’s untested. Apt itself works pretty well, but the packages themselves probably weren’t designed for this.