My Test FGT-60C here boots like this:
Total Ram: 512 MB
NAND init: 128 MB
MAC init... nplite#0
Press any Key to display configuration menue... (waits some seconds for a Key)
reading boot image....
This is the point where you could interfere. You should get the message "PRess any Key to display configuration menue".
When you press a key in time here you get into the config menu which is the menue of the bootloader.
From in there you can format the boot device which will erase firmware and config completely.
Then you will have to upload a valid firmware image via tfp.
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