I've never encountered a tech interview in any of my phone calls or on-sites.

I've tried applying for QA, but got turned down on my second interview with an engineer, because they thought I would be bored, since I already had some dev experience from a two month contract.

I've already sought advice. This included coffee with other HN users, and posting top threads. One is https://news.ycombinator.com/item?id=13726646