SD C4 and C5 firmware update SD C4とC5ファームウェアのアップデート方法
SD C4とC5（商品番号：SP100-D, SP255）ファームウェアのアップデート方法
How to Update and Flash Firmware Program for MB SD C4?
1.) Pls do not delete main unit firmware program, or you meet the following pic problem: "DCDI_eErrorCode=204 (204)", WiFi cannot be set, the SD C4 number also cannot be set. You will need to update and flash firmware program for MB SD C4, as it caused by that the main unit firmware program is deleted.