I had the same problem as you few days ago, it just would not connect.
finally the software was able to recognize the Gotec and let me reflash it.
I am not sure exactly how I got to work, but you can try few things.
I used WinXP.
Make sure your USB "thingy" has drivers installed.
1. My USB-TTL converter has 3.3v, TX, RX, GND, 5V pins, and it was recognized as COM5.
2. Verify in the Device Manager what COM PORT it is.
3. Connect the BOOT-3V with jumper
4. Connect USB-TX to Gotec-RX, USB-RX to Gotec-TX
5. Connect USB-5v and USB-GND to the Gotec-Power Connector.
6. Start the Flash software, select correct COM port.
7. Get another JUMPER and attach it to the RESET pins on Gotek.
8. click NEXT on Flash SW and then REMOVE the RESET Jumper.
9. Try to do STEP 7-8 with JUMPER on S0 or S1.
In my case some how it worked.
One more thing, if you are able to reflash it, you may have another problem, not all USB sticks work. Out of 4 USB sticks onlyt one works, LEXAR. Some say HP and Kingston work too.