Test automation engineer to Data Scientist

Not to be rude but Data Science is no longer a buzz word or something you can get away with just with any stem degree or a couple of basic courses. Not saying you can't get a job - just that there wouldn't be much security to it and getting the job itself will be difficult. On top of that you'd have to start small again. Having said all of that - ISLR book, Andrew Ng's 2 coursera courses (on youtube), any content from Karpathy is good way to do theory. For doing actual experiments and work you can try Kaggle - but in my experience work is never as easy as Kaggle.