If you find that you cannot charge your phone after the battery went dead, it could be a documented fault.
I tried the following solution, but it did not work form me:
1. Connect the charger supplied with the N8 to other compatible Nokia phones, like E72
2. Wait for the other device (E72) to start charging.
3. After it starts charging, remove the charger from it (E72).
4. Now, try to charge the N8 using the supplied charger that you used with the other device previously (E72).
5. Wait for the N8 to charge or start.
As said, the above did not work for me.
I solved the issue by attaching my phone to my PC via my usb cable. It started charging. I did not switch it on until it was fully charged.
My Nokia N8 is alive again and also charges using the charger.
I will probably make sure not to discharge the battery completely in future.
Hope this helps.