System problem. If the phone can be turned on normally, the red light flashing when charging means that the current power is low (generally less than 20% will remind), only need to keep the phone charging for a period of time, there will be a red light into a yellow light flashing, when the power reached more than 80%, the light turned green. This is a normal phenomenon and belongs to the default setting of the MIUI system of Xiaomi mobile phones.