Windows 8.1 -> 10 Upgrade keeps failing...should I just reinstall 8.1?

I'll try and retell my attempts to upgrade to 10 as best as I can remember. I'll probably forget about some attempts just because I've been at this for so long I've lost count. I've been trying for about a week.
Day 1:
-Wonder why I can't get 10.
-Click on get updates from MS, not WSUS, and there it is. (Seriously, MS, why can't I uses WSUS to cache a 3 GB ISO?)
-Update downloads (over 3 hours on my 3 Mb/s connection), finally installs.
-Reboots, gets stuck on 82% (configuring settings 29%).
Day 2:
-I wake up, check progress, and it's still at 82%. Reboot and it reverts to 8.1.
-Try again, this time Windows Update gets stuck at Preparing for Installation.
-Google my error, find this, try all the steps listed, and it still happens.
-Try all sorts of stuff, like using disk cleanup's system file cleanup to clear Windows updates, run a FixIt for Windows Update, stop and start Windows Update service, etc.
-Still fails at preparing for installation.
-Eventually restore from Acronis backup in hopes that somehow this will work, but nothing new.
Day 3-5:
-Keep trying Windows Update, sometimes it works but hangs at 82% again, other times it sticks at Preparing for Installation.
Day 6:
-Discover the boot media creator tool.
-Try to use the "upgrade" option.
-Downloads the ISO, reboots, fails once again at 82%. This time, however, I get the error message listed here when I get back to desktop.
-Try again, same results.
Day 7:
-Choose to download ISO, put on USB drive with Unetbootin.
-Run setup.exe, it runs and reboots, stuck at 82% again.
I am going insane trying to upgrade. For some reason, my wallpaper randomly turns black and then returns to what it was originally. Nothing has worked.
I was going to use the reset option after upgrading since clean install requires a Windows 10 key, which I do not intend to buy. However, it seems the only way to upgrade may be to use the reset option in 8.1, then upgrade to 10.
As some of you may know, taking the 8.1 upgrade from 8.0 prevents you from using the reset function since you don't have the original 8.1 disk. I do have an AIO rollup image I torrented, would that work as installation media? Or do I need to get an untouched 8.1 Pro x64 disk?

Also, according to my router logs, I have downloaded almost 45 GB of data from MS, so...about 15 failed upgrades (not including using my USB drive after I downloaded the ISO to my desktop)...what a waste of my 3 Mb/s connection. Thanks, Microsoft, for not letting me cache the upgrade on WSUS! You're wasting both of our connections!

The code listed said something about a failed data migration, maybe try doing the upgrade without migrating any data from the previous install ? Or doing a clean 8.1 install and then an upgrade to 10 from there.

Except that would be a clean install. You have to have a product key for 10 to do a clean install without upgrading first. And I don't want to buy 10 if I can upgrade for free.

Write down your product code, and use it again to install 8.1, then take the free upgrade to 10 which turns it into a 10 key ? If it gives you any shit about the code being used, call MS and tell them what's going on.

Backup whatever files you need to keep externally somewhere.

Do a factory reset/install of your 8 Right after that install Windows 10, then migrate back over whatever files you backed up. Then you're done.

That's what I did on my laptop reverting back to Windows 7 on launch day and have had no issues.

I bought 8, upgraded to 8.1 via Windows Store. I can't reset 8.1 without an 8.1 disk (I have an AIO rollup, but IDK if that will work since that includes basic, pro, and enterprise on the same disk).
Getting all the updates installed on 8...I do not want to go through that again.
Oh, and then of course I have to upgrade to 8.1, which means downloading that again...

You can literally go and write 8.1 ISO to a disk, and use your product key to activate. I'm not suggesting the approach is ideal by any means, but it will likely sort your problems out.

Probably best he does all his Windows Updates before launching the 10 upgrade though.

most likely I would assume yes. I did so on Win 7 before upgrading. took a while but I have had zero issues.