Just a straight re-badge of the Geniatech ATV1000 - no longer listed on their website, it's been replaced by the ATV1100. I've had one of the ATV1000 for ages, these boxes were really intended for Android 2.3 only, they weren't meant to run Android 4, that's what the newer Amlogic chips are for.
You can find the general purpose Geniatech thread over here
, the latest Android 4 firmware is here
, though with Geniatech boxes you must be at a certain SPI/firmware level before you can update to the latest version (there not retroactive so you have to install the older updates first). Think of SPI updates as bios updates and the firmware updates as the actual OS image.
If Diamond supply a version of Android 4.04 then it sounds like they've already applied the necessary updates so the one from Geniatech should work.
To force flash the the update copy the zip over to an SDcard, rename the file as update.img, unplug the ATV1000, hold the reset button down on the box then plug in the power lead, it will eventually bring you to the recovery menu (let go of reset button) and flash the firmware.
You can also run Android XBMC on these as it is an Amlogic 8726-M1 chip. There is a Android TV generic user manual from MyGica over here
which covers the various remotes used by these boxes, MyGica are the retail arm of Geniatech.
The Mali GPU is pretty weak on the 8726-M1 only 1 core and low clock speed, dont expect any miracles with it for 3D content, for a CPU speed boost install SetCPU and set the profile to on-demand as the default CPU governor profile holds the system back.