Samsung's share of the mobile phone sector in China also dropped significantly to 9.3 percent in the first quarter of this year compared to 18 percent for the same period in 2014, according to market consultancy IDC.

Increased competition from Chinese companies, such as Huawei Technologies Co Ltd, Xiaomi Corp and Lenovo Group Ltd, were partly to blame. But during the expansion years of Samsung in China, employees at BKSE had the opportunity to work in the company's headquarters in South Korea. Zheng was one of them.

Assembly line workers earned 4,000 yuan ($630) per month and had ample overtime. Zheng's take-home pay was more than 5,000 yuan a month, supervising an assembly line.

Then in 2013, overtime dried up as orders started to shrink dramatically.

A month before the factory closed, more than half of the assembly lines were mothballed.

"We later found that the South Korean management team had left the company on June 10," Zheng said.

"Although there were no orders for that month, all of us were still working as usual before the company announced the closure of the factory on June 23. It was a massive blow."