On Tuesday's edition of Tech Teardown, Motley Fool tech and telecom bureau chief Evan Niu sits down with host Erin Kennedy to look at five of the biggest stories affecting tech sector investors this week. He looks at three big announcements from the Mobile World Congress trade show that kicked off in Barcelona this week, from Nokia, Samsung and BlackBerry. Evan also looks into T-Mobile's aggressive pricing and marketing strategy, how quickly it's winning back branded customers, and whether or not it's worth the trade-off of some damage to the company's bottom line. And in the final segment, a look at LinkedIn, its official announcement that it will be launching in China, and what its prospects may be there.