I applied online. The process took 2 months. I interviewed at SpaceX (McGregor, TX) in Oct 2019
Interview
Pre-screening phone interview followed by a full phone interview. Finally an on-site visit with a technical presentation and panel interview. Afterwards I was supposed to hear back by the next Wednesday. I still haven't heard anything (it's been 3 weeks) and have since accepted another position.
They drew a circuit and asked me to diagnose the problem. I could use them as my "multimeter" by asking questions about what I would read across different nodes.