It would appear from a current user issue that on the HD51, a usb flash does not reflash the HD51 boot partition.
If it is initially flashed with an OE-A image that is not an issue, but with OpenPli their boot partition is different and will cause issues. Other multiboot receivers are not impacted as they derive the boot partition differently, but with the HD51 its really down to whoever sets up the receiver meta files and as we know OpenPli do it the correct way (!) and differently.
I can (probably will!) put code in to check the boot partition and file layout and if not there either use the method created for OpenPli (which I dont like - its clumsy) or an alternative.
However, for the time being is it possible not to provide buyers for the HD51 with an OpenPli image option?!