so what's the trick to upgrading the firmware on a 4.20.7 box? I tried everything: from web, tftp with boot_wait hack, multiple reboots with hard resets...nothing...firmware won't let me upgrade...keep getting upgrade failed or else the firmware loads up when i am using tftp with the boot wait hack and so it starts saying invalid passwd. i cant downgrade 4.20.7 to anything else either. is there perhaps another firmware i can install first, and then upgrade to dd-wrt after that? what's the magic trick???