The video omits crucial details aside from the physical act of removing the original and soldering the new NAND. I know for a fact failing to copy original details results in failure to restore iOS with specific error codes, so I wonder what this video did. I've successfully done this many times back in the iPhone 6S days where the original chip was desoldered, read by a Chinese-made reader, and finally the identifiers cloned to the new chip. I sold phones upgraded from 16GB to 128GB for a meager profit, but it was for fun.
How can the new chip work if the original chip is milled off completely? I would be surprised if you could read all necessary identifiers through iOS/USB software before milling unless the device was jailbroken and read that way. Seems like a big oversight for Apple not to implement simple countermeasures to make it a little bit harder, or that Apple would undo protections they had back in the iPhone 6S days.
How can the new chip work if the original chip is milled off completely? I would be surprised if you could read all necessary identifiers through iOS/USB software before milling unless the device was jailbroken and read that way. Seems like a big oversight for Apple not to implement simple countermeasures to make it a little bit harder, or that Apple would undo protections they had back in the iPhone 6S days.