Originally Posted by
Tricon
Thats....not how that works at all. Processor's inherently do not have any storage. Maybe some volatile cache, but thats moot. There's a boot loader that looks for the local image of the firmware on the ROM. If the bootloader or ROM image fail a checksum check, then it won't boot. The boot loader has a method for overwriting the current ROM, but it will check and make sure its incrementing the version number only. Your only hope would be to hex edit the old firmware and try to pass it off as an upgrade, but they have a few other checks they do to make this pretty much impossible. They are locked down pretty tight, understandably so.
Their terminology was wrong but they're mostly correct. You can't just use their firmware update software and hand over the downgraded version. You need to do board level flashing manually. Either by desoldering the EEPROM and using a flashing tool directly, or using a special clamping jig to interface with the EEPROM in situ.