tiny4412 1312增强型底板 带miniUSB，使用miniTool刷机不成功，显示单板无法连接
因为没有串口线，按安装说明书上的说明，使用miniUSB连接+MiniTool来烧制系统。
Note: the following three steps only apply to 4412/210/6410
1. Flash the Superboot to an SD card with SD-Flasher;
2. copy the "images/FriendlyARM.ini" from the shipped DVD to the SD card's "images" directory;
3. Open the "FriendlyARM.ini" file in the SD card and add one line "USB-mode = yes"：
USB-Mode = yes
Connect board to PC：
1. Switch S2 to SD or Nor Flash. If your board is 2440 please make sure no SD card in the SD slot or USB-Mode = yes
2. Power on the board it will enter the USB mode. Connect your board to PC via a USB cable;
3. If the USB connection is a success , 210/6410 will show "USB Mode: Connected" on its LCD;
按上面操作后，miniTools界面下面显示Board is not connected or Superboot is not in USB download mode。
这是为什么呢？SD卡里面的images应该都是好的，在普通版上烧制能成功。也加入了USB-mode = yes。
哪位大神指导下？
