Latest Preview Program Update Files?

Looks like my internal 512GB internal SSD wrecked itself and any recovery attempt of the Update files ([System Update]\A and [System Update]\B) ended in failure.
Now I switched back to the original HDD and tried all kind of different updates like OSU1 (08/December/2016), OSU2 (04/September/2015) and the “Factory Reset” File (01/December/2015) and none of them worked, just “updating” up to 3 percent, creating a few files on the HDD and failing after that.
My guess is that the console doesnt want to “downgrade” and refuses the updates.

My current version:
15046.1001.amd64fre.rs2_release_xbox_1703.170226-1700

Since Im in the First-Wave Preview Program I need the latest update and I hope someone has access to those files.