The system was build a month ago but all of sudden it was shutting down and now it doesnt turn on. Could it be a cheap 380 watt power supply that came with the chasis?
Welcome!
Yes it can be the cheap PSU that came with the case! It can also be a lot of other things! List your full system specs (brand model) so we can better help you!
Yes, it's hard to make any kind of diagnosis without knowing the parts. If that 380W PSU was a Diablotek or Logisys (I've seen a lot of them in Newegg and Tigerdirect bundles lately), then hopefully it didn't take any other parts with it.