Sorry to resurrect an old thread. I got hit by this bug today. Like most people, I didn't feel like going back and replaying forty hours, so I cracked open the CreationKit and script editor for a couple hours. I think I have a minimal solution. TL;DR The best way to avoid the glitched shard bug entirely is to get Mzulft LAST. It seems the quest designers expected you to get the shards "in order" (Arkngthamz, Raldbthar, Deep Folk Crossing, Mzulft), but of course the game doesn't really tell you that order. The quest aliases pointed to the shard refs are populated dynamically by a script, at the same time the names change from "Glowing Crystal Shard" to "Aetherium Shard". But the script that populates them stops after you get the Mzulft shard, and if you haven't got the others, their references stay as null (and their names don't change). Then the Dwemer Mechanism at Bthalft runs this code: if player.getItemCount(null) >= 1 ... Obviously, this line will never be true, and the mechanism can't be activated. The mechanism's script has a variable "animState" which never gets updated. (If you know how to do this from the console, please let me know. The problem is it's on a ReferenceAlias script and not a quest script - also, it's a local variable and not a property) Anyways, I took the "setstage" idea posted earlier in this thread and came up with a way to bypass the mechanism but still open the door to Bthalft the "right way", so that you can go back in if you want and you don't need to clip or teleport anywhere. It's a bit long, but most of the length is manually running the animations for the elevator mechanism. I verified this works in at least two bugged saves. Note that anywhere I put a comment between commands, you need to exit the console and let the game run for a few seconds. There's three quests running simultaneously here, and each time one updates it needs to signal the others to run for a moment. Fragile coding, Bethesda.
; Start anywhere in Skyrim EXCEPT Bthalft. There's a trigger that won't activate if you're already there.
setstage dlc1ld 30 ; if Raldbthar is bugged
setstage dlc1ld 40 ; if Deep Folk is bugged
; Go to Bthalft and talk to Katria
; Open the console and click on the Dwemer Mechanism. The ref id should be xx013f26
sae crest01
; wait for anim to complete
sae crest02
; wait for anim
sae crest03
; wait for anim
sae crest04
setstage dlc1ld 175
; Talk to Katria. She tells you to take the crest out.
setstage dlc1ld 179
sae take
; wait for anim. You get the idea.
setstage dlc1ld 180
; Stand clear! Wait for rumbling to start
sae open
; last anim, I swear
setstage dlc1ld 182
; Optional - Remove the shards from your inventory
; (because we bypassed the script that usually does it)
; (and because they're quest items)
player.removeitem 200575c 1
player.removeitem 201433c 1
player.removeitem 201433d 1
player.removeitem 201433e 1
After this, I took the elevator and finished the quest as normal.