unable to flash, please help

Hi, I have built a flashing cable (pin 1, 3 to ground, green/white/red at pin 4, 5, 6, pin 15 has 12 volt). I use Motorola NNTN5405 to build this cable. It has 3 black wires internally. Two black wires are interconnected to the shield. I am not sure the 3rd black wire and cut it out. But when I try to flash, the bottom of the flash window shows “COM1”, not USB. I know the cable is not recognized by computer. I am using window 10. How to solve this issue? I checked my ground wire, and it is connected to the USB port shield (is this correct?)

Checked wire again. It turns out that 3rd black wire is connected to one of 4 pins in USB. I reconnected that black wire to ground. I believe I have done everything I could. But still, window 10 can not recognize USB and display COM1. I just wonder if it is issue with window 10? should I install some USB driver?

Did you make sure the radio is powered off?

Did you follow the instructions here?

Yes. But i have not tried to install drivers and others specified in the error session. this flash guide is written for window XP/vista/7. I am using window 10. So i will follow up with special instruction for window 7 64 bit.