I am sorry. I carefully monitor your epic...
I wanted to ask one question about formatting.
On the screenshot, you do not have a check mark "Set partition as not bootable", but it is worth using "Use 64hd/32 sec if possible". I always formatted with reverse settings. I think this can be significant. Especially the first one.
Perhaps you need to format again?

And another one about last action.
Many alpha100s ignore the last_id.bin file and after the reboot command and reboot they start to execute the update.txt command file again. It is required to turn off the alpha in time with the button after waiting for the reboot immediately after the "Garmin" appears on the screen..
Sorry my English...