Instead of soldering on a device like an XTA I would do some more checks beforehand.
Get another (or even some other) USB to serial adapter. I've heard many stories about these cheap things that sometimes work and sometimes not. Manufacturers seem to change chips inside so even the same brand might work or not. This is regardless of the adapter is to be seen in device manager...
Find a PC with a true serial port, a colleague with a working USB to serial adapter or a serial device server (ethernet to serial adapter). Just to verify if your XTA is really broken.