LED light on Razer Blade 17

I have purchased the above laptop this week. The first one was returned after technical advice from the retailer because the laptop power led was not showing properly. When it was first plugged in to charge there was no light, and it wasn’t until I pulled the adaptor out to pack it away for return that a light appeared. The light didn’t stay on and the laptop was then returned. The replacement received today showed a similar behaviour, but is now flashing white with the power connected, the laptop asleep and the lid closed. Is this normal behaviour? How do I know when the laptop is fully charged in these circumstances? Derek Clements