Apple has announced an iPhone 8 Logic Board Replacement Program. The company says it’s determined that a small percentage of the devices contain logic boards with a manufacturing defect.
Affected devices may experience unexpected restarts, a frozen screen, or won't turn on. Apple will repair eligible devices, free of charge. Affected units were sold between September 2017 and March 2018 in Australia, China, Hong Kong, India, Japan, Macau, New Zealand, and the U.S.
If your iPhone 8 has an eligible serial number, Apple will repair it, as mentioned, free of charge.