According to the files in the archive terminal Ren used to work at following office: Neo Berlin Business Street, CyberGaia Corporation, Office F13
It is the Corp Lobby that can be accessed from the Business Street.
This is the low-spoiler guide for "Visit Tina's Father's Old Office" puzzle in Encodya. Unlike in normal walkthrough, you get gradual hints on how to solve the puzzle. Click the big button below to see your first hint. If the hint contains a spoiler, you will be warned about it before clicking.