The WF-1000XM4 charging indicator flashes red during wireless charging

If the charging case indicator flashes red, it indicates a rise in temperature.  Remove the charging case from the wireless charging pad, let the charging case cool and begin charging again.

Note when using the wireless charging pad:

Failure to follow these instructions may lead to malfunction and/or damage to the headphones, charging case, and/or wireless charging pad. To avoid any damage or malfunction, always carefully inspect for the following before charging:

• Charging may slow down or stop if the charging case becomes misaligned with the wireless charging pad. For details on how to set the charging case properly on the charging pad, refer to the manual of the charging pad.
• Be sure to remove anything attached to the charging case, such as covers, when charging.