AHT boot: Failed to Initialize Product Driver

Experiencing some problems with my late-2012 iMac 27-inch, and it does remind me of these kind of problems with a mid-2010 MBP of mine. It turner out it had one of those bad motherboards / graphic cards.

So I would like to test the hardware of my iMac. But, when booting AHT it throws me an error: '

Failed to Initialize Product Driver. Status = E'

After that it won't continue booting into Apple Hardware Test. I think this confirms some kind of hardware problems, but until I can use the test I'm not sure. Any suggestions?

Thanks and best regards,

Maik