Thank you and appreciate your pointing me to a project that i can learn from. While i agree that modern-day PCBs often have their magic inside an FPGA/ASIC/MCU, the overall system is still defined by the PCB. If something doesn't work and i suspect the problem isn't in the software, then i should still be able to understand the schematic and follow the signals in the PCB at appropriate points to debug the problem. While there are lots of "hardware hacking" info, i can see no systematic approach to the problem. Perhaps with more study and practice i will learn to identify the key areas to look for and understand.