Neon-green lights dotted the homey Los Angeles venue and spacey synths greeted fans before an audio montage of broadcasters repeatedly cheered Jessie J's name and the birthday girl appeared live in front of 14,000 fans.The U.K.-based pop star donned a sleeveless cobalt-blue lace jumper with matching gloves before digging into "Masterpiece," the first song of Jessie J's phenomenal one-woman production entirely hosted from the comfort of her home and broadcast via Instagram Live on Friday (March