[fshrago]

I have a lumia 920 and it is now no longer booting up.

The battery was charged overnight.

When I switch on the phone I get a battery with a question mark in it.

I have tried soft reset (power+vol down) and hard reset (power + vol down + camera) neither worked

I have also changed the battery from a different lumia 920 (which was working fine in the other phone) but this also did not help.

Any ideas?

Would flashing the phone help? Any tips or guides on doing that?

Thanks

[Farnic]

Do you mean it is no longer booting up unless it is plugged in? My assumption would be your battery has bit the dust, as the ? over the battery icon probably indicates the phone cannot detect a battery at all.