The walls in the Hall of Epochs that block your way to the platform for shooting the Arrow of Extrication won't move. Usually you must defeat the lich, push the button behind him and then you're set. This time, I come back to the walls and nothing has happened. I have reloaded the game and started from previous saves. Does anyone have a work around, or perhaps a cheat to progress the story? Any other advice?

Thanks

P.S.
I'm running on a Windows 7 PC

I was thinking I'd just cheat and code the scroll into my inventory.... But I don't believe I can leave the way I came.

Update for the thousands of people hanging on my every word:

I used the code to get the scroll. I then left the Hall the way I came- only to realize the script still thought I was in the Imperial Library. So, I tried to sneak back into the library just to trigger the script. I found that it's locked and the key doesn't exist. I used a teleportation code to get inside, and then exited the quest way- down the chimney. However, in my sneaking around I had forgotten to take off my Dark Brotherhood robes, meaning I wasn't wearing Jak's boots. I survived the fall, though, and the boots remain in tact in my inventory. Because I was never able to unlock the keystone, I was stuck under it. I used another code to teleport to the Applewatch farm (because I like it there). From there, everything with the quest was normal. The Fox spawned and I finished the Thieves guild quests without a problem.