I have same problem and this is the way worked back
I had encounter this problem just this morning cz I "repair" my phone by using PCC.
I let it overnight cz when I did it already midnight.
When morning I woke up, I found that the phone was totally shut down and I was unable to turn on the phone.
I was worried at that time and even I charge my phone I cant switch on the phone.
I let the phone charge for very long time, using the adapter charger. Then I try to pull out the sim card and wait long time just put back the sim card, suddenly the phone switch on by itself.
But i really dunno why. Hehe
This is my way. Hope will help you