After killing Barrett you were left with only one clue: Head to the Hengsha Court Gardens in Shanghai. Then again, the guy who told you that also wanted to send you to hell.
o Meet Sarif in the Penthouse [1000 XP]
o Meet Pritchard in my office [1000 XP]
o Confront Sarif Aout the Security Leark [1000 XP] + [Silver Tounge 1000XP]
o Meet Malik at the Helipad
Back at Sarif Industries, head into your office and check your email. Don't speak with Pritchard, ignore him for now. You can re-explore the ventilation shaft in the southwestern part of the lower area that leads towards the Helipad. It now contains [P.E.P.S. AMMO] and [TRANQUILIZER AMMO] .
William Taggart & Isaias Sandoval
Head inside the penthouse by using the elevator in the main hall to meet Taggart and his assistant Sandoval. Although the dialogue has no influence on the story, it's worthwhile to get as much information from Taggart and Sandoval as possible to better understand the story. Speaking with Sarif gives you your next mission [1000XP] . Head to Jensen's office, then speak with Pritchard [1000XP]. He'll tell you about a security problem in Sarif Industries' network, and he wants you to talk to David about this.
David Sarif Social Battle
David has the personality type Alpha, so you'll need to watch what you're saying since he is after all your boss. Carefully formulate your thoughts and stay with the subject. Your first answer should be Redirect, but after this the conversation is semi-randomized and you'll have to listen to David carefully. Winning this conversation also grants you the YES BOSS achievement/trophy. [1000XP] + [SILVER TONGUE 1000XP].
You had an argument with your boss, David Sarif, and won.
Return to Jensen's office and read all emails on his PC. Speak to Pritchard outside of the office afterwards. These steps are important so you can later activate the Acquaintances Forgotten Side Quest.
When you've fully explored Sarif Industries, bought everything from the shops in Detroit you need, and explored the city thoroughly, depart by speaking with Malik at the helipad [1000XP] . You'll be back later in Detroit for unfinished business, but things'll be slightly different when you return.