Dell XPS M1530 does not turn on

You can not turn on the computer
If after checking all the cables and contacts your computer does not turn on it might mean that was damaged power supply unit. To remedy this problem must be installed on your computer a new power supply.

If after replacing the computer starts normally, it means that the old PSU is faulty.

If, despite replace the power supply the computer still does not start then guilty of this fact it may be damaged motherboard. Then the only solution is replace the motherboard.