Dell 2330dn imaging drum counter reset

How do we reset the imaging drum counter?

We replaced the imaging drum because we were getting the PC LIFE WARNING... but there wasn't any instructions in the box that said how to reset that counter. I've done it in the past because there were instructions in the box on how to do this...

I've tried to look this up on the net, and haven't found anything for the 2330dn... I don't feel like calling Dell, as I'll be on waiting list or put on hold...

Does anyone know the combination to do so? I know the front door has to stay open when the power is off, and I think you have to press some keys while powering on the printer...

Anyone know the combination?