According to this article from January 11, 2021, Turkey states that it will only purchase the second party of S-400s if the tech transfer will be included in the deal. Apparently, as of March 3rd, these talks are still underway, so no tech transfer was approved by Russia at that point, and I do not see any news on the matter.
So why buy S-400? Well, looking at this article, it might be an attempt to driving down costs of offers. While Turkey states that it does not see S-400 and PAC-3 as competitors, the data on these systems suggest that their stated capabilities are similar, and the cost of Russian system seems to be significantly lower on per-unit basis than the American one. So even if Turkey won't get the tech it wants in the end, at least it will get more batteries for its money.