A direct call from the Hiring manager. Next step, I was called at the office for in-person interview. This was a panel interview with all senior engineers and managers. The interview process went for 6 hours in total.

Very negative experience. They strung me along when the hiring manager clearly had another person in mind for the position. Interviews were easy except the hiring manager asking 'gotcha!' Style questions like how I would bring in money for the company. I thought the position was for an engineer, not a sales rep. Good Ole Boys Club vibes. I had 2 phone screens and a 4 hour panel interview for which they required a presentation from me. For the salary you're offering, I'm not sure why you're doing Fortune 500 interview grillings. Process was slow and took 2 months.