As far as I known is there no bbs software for these BCM7424 cpu, as also no nand flash script.
Jtag pins question, I think, the four pins P301

Issue, white LED
Be sure that it failed to read from the usb ports, use a usb stick with an activity led, or monitor it with the rs232 terminal programs as putty to see if it"s doing an attempt to read from a usb stick.
You could also try to add the force.update to the usb files.
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Johnny B.

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