I just performed a fresh flash with 7.2 RC.
A step by step tutorial.
1. Put a stick (FAT32 formatted) in the upper USB slot. That's at least the one I used.
2. Power on the box.
3. The display shows ENUP.
4. Pust the power button.
5. Output on the display shows something like F500 and F700. Not exacly noticed. After about four to five minutes the Amiko bootlogo is shown and the display shows run and then boot.
6. Due to some odd / unknown reason restoring the just created backup appeared not to be possible in the upper slot. The stick wasn't recognized in 7.2. RC. When putting the stick in the lower slot and performed a factory reset, the backup was restored as desired.
thanks a lot i had success !