Curtis DVD8723, portable dvd player, does not boot, why ?

I ran into problems with the curtis portable dvd player DVD 8723.
I usually take good care of electronic product (no mechanical schock, no humidity etc... ), however I had to exchange this portable dvd player already and I still have the same problem.

Problem:

First cause of the first exchange. The power supply was connected on the unit then on the wall. When connected on the wall, I had a short circuit noise in the power supply. The unit was tested with an other power supply and never when back on. No access to menu, did not seem to power the dvd motor...

Now:
The unit was working fine on its battery and was shot down through the dc on-off switch integrated to the dvd player (equivalent of a hard shut down...). When I attempted to reuse it, It simply did not initiate the opening sequence. You can't acces the menu or set up function. You get kind of a low backing light on the screen. It does as if there was low battery power condition. The dvd motor does not seem to turn. This even if the unit is on the power supply.

Is this system particularly sensitive to variation of voltage ?
Did I blow the circuits by doing a hard shut down ? I would rather like to suspect a minor problem with the unit but which one ?

Thank you for helping.

Frank.