Didn't use the Dreambox over the past few weeks because of this problem.
Opened it again and looked for any components that might be discoloured, leaky capacitor, or any other visual sign, but UNFORTUNATELY no such signs.
So closed the box, thought it might be the latest Gemini image 4.6 might be causing it.
Flashed with the previous version 4.5 but during setup, it shutdown while doing the satellite scan.
Waited few minutes, did the rescan again, and this time it finished the whole cycle.
Made minor adjustments, put few channels in the Favourite bouquete,
viewed channels over the past three or four hours (I hope I am not jinxing it now), still no abrupt shutdown.
HDD is still out.
Fan is blowing on it, as it is a really hot day today.
Hope it stays this way (the Dreambox, not the hot weather
)