I have contacted the ATC about this problem and this is their answer:
We rarely encounter this situation, we can suggest to try a hardware reset. At present, there is no way to update the firmware of ATC-1000. It is a one-time burn chip. We now recommend our new ATC-1200 which is more powerful. It can customize the customer’s web interface logo and upgrade the firmware later.
Considering that you have already tried the hardware reset, probably there is no way to solve the problem. But consdering the limited cost of the ATC-1200 you can consider to substitute the converter.