Hi. I had problem like this, now resolved. My device is iAudio 9+ otherwise it's not matter.
You can find some solutions on the web but... maybe you can not do proper result first or second time. It comes because of some differences for so lot of devices.
I used this method.
How To Recover your Bricked J3 using Tcctool iAudiophile net Forums
Only one way working for me.
1. Prepare drivers and firmwares. Tcctool and Windows drivers for USB flashmode. Latest FW for your iAudio from Cowon Korea site. Unpack all files/folders into special directory in root of your Hard Drive (c:\COWON for example).
2. Boot your PC in compatibility with non-authorised hardware mode. Press F8 button when PC loading and choose Drivers signature disabled mode.
3. Turn off your iAudio with reset button. Press both M(enu) and VolUp buttons and boot on power. Screen doesn't fire but device standing up in flashmode. Connect USB cable to device, then to PC. On Windows Device Manager you must find new Unknown Device. Install drivers manually from your specific directory.
4. Run on PC new task CMD, e.g. terminal window. Change work directory to your specific, f.e. cd c:\COWON
Run execution tcctool.exe -d cowons9 "name of your FW file"
Attention, your FW file (iaudio9P_fw.bin for me) must be in same directory with executable tcctool!
5. After flashing your iAudio must be connected to PC immediately as USB flash device. So you must copy all firmware files (named *.bin) to root of your Cowon device memory. Then reboot, your player must updating firmware and working fine. If still no, try use tcctool to boot on once more, then reboot normally. Copying FW files again doesn't required.
Hey you don't give up!