For what it’s worth, I got tired of messing around with the different methods proposed for updating to the anniversary edition and came up with my own somewhat unconventional way. I wanted a clean and easy way to do it because both my wife and I have X80 Pros and I like to experiment haha. I’ve probably wiped and redone each of them four or five times now.
I took the back cover off (one of the tablets came with a faulty SD card socket so I had already learned how to take the back off when I replaced that) and attached a 4.4 VDC supply straight to the red and black leads of the battery, attached an external flash drive and pointed Windows to it when it complained of not enough space. Wake up in the morning and it’s done. I limit the current to 1 amp. If the battery is charged all the way at the beginning it draws less than that and by morning is drawing just what is needed for the tablet to idle, maybe 150 mA.
Like I said, not a real option for most but I figured there are some tinkerers in the group here.