It appears that the SYS is bad. My suggestion is to reflash the firmware, which you said that you tried already. But this time, keep on doing it until it works. You said that your Pronto is doing the 4 beep trick, do you mean it's in the 4 beep loop, keeps on rebooting itself every couple of seconds? If so then when you do the firmware update, don't press the reset button as prompted on the computer. Instead let it reset itself. It may happen on the first try, or it might not happen until the 15 or so try. But keep trying. Also take the batteries out for at least 8 hours, 24 would be the best though.

Rob