How to switch from MKL to OpenBlas

Has anyone switch from MKL to OpenBlas?

After installing fastai on ubuntu
Then i try to install openblas

conda install openblas
conda install numpy jupyter ipykernel blas=*=openblas

It took almost 10 min and complaints that
package conflict but I have no idea how to solve it.

Any one have successfully switch to openblas?
Kindly give some hints