I would:
- Go to the Cavern
- Go the the 1st Ed Sullivan Show performance in 1964
- Go to The Beatles’ main gigs (like Washington, Shea, or San Francisco)
- Join them in India to see what happened there
- Watch the rooftop concert
- Be in the Apple Scruffs
- Convince John, George and Ringo NOT to work with Allen Klein
- Attend to the performance Elton John and John Lennon did together
- Attend to many Rockshow gigs
- Attend to Concert for Bangladesh
- Convince John and Paul to go on SNL
- Save John and George of course
- Convince The Beatles to play during Live Aid in 1985