TIANJIN, China — Zhang Sitong was saving a friend’s phone number on his Samsung Galaxy Note 7 smartphone when it started to vibrate and smoke. He threw it on the ground and told his friend to start filming.

Two employees from Samsung Electronics showed up at his house later that day, he said, offering a new Note 7 and about $900 in compensation on the condition that he keep the video private. Mr. Zhang angrily refused. Only weeks before, even as Samsung recalled more than two million Note 7s in the United States and elsewhere, the company had reassured him and other Chinese customers that the phone was safe.

“They said there was no problem with the phones in China. That’s why I bought a Samsung,” said Mr. Zhang, a 23-year-old former firefighter. “This is an issue of deception. They are cheating Chinese consumers.”

Samsung, already reeling from its embarrassing and expensive decision last week to kill the Note 7, has a particularly vexing problem in China. On Tuesday, China’s powerful state-run broadcaster, China Central Television, or CCTV, criticized the way Samsung tested its phones and asked whether its claims that the phones were safe and reliable were “fabricated falsehoods.”