I was in the exact same boat for several years. After repeated rejections, I took a break from interviewing for a couple years. I already had a job so I could afford to do that. I realized that I was applying for the wrong type of jobs. Instead of hands on IC roles, I targeted engineering manager roles since I have quite a bit of experience managing small teams. I recently landed a job with a FANG as an engg. manager. Even though there is a coding component the main focus is on systems design and team leadership, also I think there is less age bias for EM roles.