How do I do a Hard reset when the pc is in a windows update loop?

This weekend my modem/router died. But it was in a crazy state where my lights were flickering. Weird. While the Cox tech was out to fix that, my system decided to do a Windows update. When the modem got swapped out -- the lights stopped flickering ( I swear) but not my pc is in the spin cycle. The message on the screen says "I could not complete the updates. I am in the process of removing. Do not shut down the system". Something like that. It has been in this state for hours. I did shut down. And I tried pulling the plug from the wall but it came back in the same state. I don't have windows disks. I bought my system already configured from Dell. Any help would be greatly appreciated.