Bit of a weird one. PDN was working great. I put it on standby and left if for a couple of hours. Couldn't switch it back on. Reset didn't work so I thought maybe the battery had run down completely. Plugged in the charger but no red charge light. Thought to myself it was hosed. Took the back off and unplugged the battery. Reconnected it and it fired up no problem. Seems to be working fine again.