If you are still stuck, post your debug.log (from Opcom software) and the exact behavior of the LED (solid, blinking 1Hz, blinking 5Hz) in the forums mentioned above. The community still keeps Opcom alive because – when you know how.
is on your board? (Look for a square chip labeled PIC18F...) are you currently getting? (e.g., "Interface not found") car model and year are you trying to diagnose?
: Many version 1.99 interfaces are not flashable ; they come pre-loaded with this version and may be locked or lack the necessary bootloader to accept new hex files.