To become a mentor at 500 start-up you must understand how the mentor program works:
1. Founder reaches out to mentors through founder's own network
2. Some mentors may be interested enough in founder/start-up to take a meeting
3. Mentor might then start providing mentoring (but not as part of the "500Startups Mentor Program"), or may refer start-up to Dave McClure
4. Start-up may become a 500Startups start-up - this decision is made by Dave McClure and his inner circle
5. If selected to be a 500Startups start-up, which typically (always?) includes investment by 500Startups/Dave McClure, the start-up will start receiving referrals from Dave and his team to various 500Startups mentors for short or long-term mentoring on specific business issues
6. Additionally, as noted by Christine, once part of 500Startups, the start-up may attend presentations given by 500Startups mentors
7. Mentor secret powers may lead to additional weird and wonderful effects, not yet fully understood by anyone.

Besides if you do have any questions give me a call: https://clarity.fm/joy-brotonath