I bought a ICX6610 from ebay that turned out to have a dead serial port. I could not find any serial repair info so did it myself, thought this should be available for people who run into the same issue. The serial driver chip is a 3232 chip on the underside of the motherboard near the two square multi pin connectors. The 3232 chip may be dead or any of the capacitors on either side of the circuitboard board near the chip. Measure the caps for short circuit and replace, and/or replace the 3232 chip. Other fix is a USB-TTL adapter straight to the channel one RX and TX pins of the 3232 and the switch will start talking through that. 
