My four years old PC won't turn on. When pressing the power button there are very short lightbulb flashes in CPU and GPU, and sometimes the CPU-fan moves an inch. After that no signs of life. All the cables should be okay. The problem occured after I had cleaned my PC with pressurised air, but it shouldn't have taken any damage during the procedure. Should I just straight get a new power source or is there a possibility that the problem is elsewhere?