Mobile manufacture giant Samsung Electronics Co Ltd officially announced on Friday that a software update for Galaxy Note 7 smartphones will be released mid-December in the United States preventing them from charging and functioning as mobile phones, rendering them useless.

The smartphone maker said that more than 93 percent of all recalled Galaxy Note 7 devices had been returned as a part of its exchange program in the United States.

The U.S. Transportation Department and other agencies in October ordered Galaxy Note 7 owners from carrying the devices or stowing them in checked baggage during flights following reports of fires in replacement Note 7 devices.

However, Verizon Communications Inc said it would not take part in the update because of the added risk this could pose to Galaxy Note7 users that do not have another device to switch to.

Samsung Electronics, the world’s biggest maker of smartphones, was quick to blame the battery for causing some Note 7 devices to catch fire. It has since widened its investigation into the exact cause of the fires in its near-900,000 won ($780) phones after replacement phones using batteries from China’s Amperex Technology also caught fire. But for Samsung SDI the damage was already done, analysts said.

In the shadows of Samsung Electronics’ (005930.KS) Note 7 smartphone crisis, affiliate Samsung SDI (006400.KS) is quietly reassuring anxious clients including Apple Inc (AAPL.O) that its batteries are safe.