So I have started chapter three and opened the large gate for Mendoza. He tells me to move forward and check for traps, but when I did this I glitched through the trap that attempts to smash you, and it closed behind me. I played with the lever and could not get it to rise, so I proceeded on my own up to the part where I am tasked with finding a map. I saved after this happened (which was unwise), and there is no save from before I glitched through the tunnel.

I decided that I should come back to Mendoza and get the quest back to working properly, so I returned to the tunnel. The gate is now up, but if I walk through and talk to Mendoza he offers no new comments to me. I can walk back and forth through the gate without being smashed no matter where the lever is. The game has not given me a "quest complete" notice for The Tunnel -- it is listed as incomplete.

I have tried marking it complete with the console and speaking to Mendoza, which does nothing. I have tried closing and reopening it. I have also tried (as I saw suggested to a player in 2010 on this forum) to attack Mendoza and lure him to the drawbridge by the lava. This does not cause him to trigger the next quest as it did for that previous player. As far as I can tell I am stuck.

I was wondering if anyone had any fresh advice for me on the situation.
Thanks in advance either way.