Win 10 has locked my PC so that it will not power on

[LeeB]

I'm not really sure whether or not 10 is actually installed- I think probably not completely. Scenario: downloaded on Jul 29 so as not to lose the free upgrade. Took a few tries, but next day thought I had it happening. It was 'configuring' for about 4 hours when this message displayed in the bottom right corner: 'Windows 7 Build 7601 is not genuine.' - it is genuine. The screen went black and the cursor went to the middle of the screen. Could not do any function, couldn't get to a menu. Did <CTL> <ALT> <DEL> to shut down and restart, several times. Finally, with no progress being made, I physically pushed the button on the tower and shut off the machine. Now comes my problem: it will not power on. Yes I checked all the connections. The PC is a Dell 530 tower unit. I have a System Repair disk for Windows 7 Home Premium 64 bit if I could get it to turn on. If it restarts in Win 7, that's fine. I could begin all over.

 

[LeeB]

Reading another post, discovered that I didn't turn off Avast beforehand. Apparently doing that solved his problem.

 

[LeeB]

I think I need to repost this in Installation, Setup and Updates. Will try now.