Some problems may require that the phone is restored while it is in DFU (device firmware upgrade) mode. Doing so may resolve issues with Exchange, an inability to send and receive MMS messages, device slowness and other problems. Постоянных кодов нет, меняются они, как правило, раз в год и бывают https://www.saludcapital.gov.co/sitios/VigilanciaSaludPublica/Lists/Contactenos/DispForm.aspx?ID=2972663