Applied online. I did have a fairly high-up contact that I asked to refer my name to HR/hiring managers, but I never heard back from him, so I'm not sure if he did anything. About a month or so later, I got an email to schedule the initial HR screen, which made sure I was over 18, eligible to work in the US, wasn't a reptile, etc...
Then, an engineer called me a couple weeks later to talk about the program and my qualifications. Then a couple weeks after that, they rushed me out to Cleveland to interview with four engineers, tour the plant, talk benefits, etc... I got a job offer a couple days later and accepted. Be prepared for HR to be somewhat incompetent in scheduling things. They were super nice and friendly, though.
I then got a background check, took a drug test (hair for THC, urine for nicotine), got a physical, and got flown back to look for housing. Lincoln paid for my moving costs, which is nice, but be prepared for the whole process to be convoluted due to everything being subcontracted out to several companies. Don't get stressed. This is typical for corporate life, I hear.