You will need to fight a bunch of enemies and a mini boss, just toggle god mode 'tgm' if you haven't already and whittle them down. Once you get to the Forge there are two valves on either side you can use to turn off the steam. continue along the path, torches will light along your way. follow the quest steps now as they are self explanatory, then go into the Forge. thankfully Dovahkin has google maps installed so teleport 'coc BthalftExterior01' and kill all the bandits that may spawn here (do not use killall as it may kill Katria). While you're here, grab 5 Dwarven metal too. Talk to Katria after if she approaches you. teleport 'coc Mzulft04z', the Dwarven Storeroom, and continue forward, again if any doors are locked just no clip through and pick up the shard (unmissable). Then you need to kill all the enemies and you can pick up the next shard (unmissable). if the door is locked here, just no clip through it. teleport 'coc RaldbtharExterior04', toggle no clip 'tcl' and fly into the roof you just spawned on, then hit the lever to travel down to Raldbthar Deep Market. teleport 'coc DeepFolkCrossingExterior02', the shard is behind the pedestal in front of you. Adding them to your inventory does not work. now you will need to locate and manually pick up the rest of the shards. enter the gates and pick up the Aetherium Shard, then talk to Katria again. toggle no clip 'tcl' fly and hit them in this order: bottom left, bottom right, top left, top right, middle. continue along the linear pathway for a little while until you reach an area with 5 tonal locks, Katria will talk to you about hitting them in the correct order. continue along the path and speak with Katria, you can skip dialogue with left click. teleport 'coc DLC1ArkngthamzExterior02' then go inside the large door where you spawned to enter Arkngthamz.

This quest is a bit screwy with using CCs to advance the questline so you are going to have to do this 'legit' and follow the actual questline making sure to fulfil each objective as it comes:

'sgtm x' speeds up the game, x is how fast (sgtm 10 means 10x speed, sgtm 1 means normal speed etc) *** Spoiler - click to reveal *** 'tgm' toggle god mode (infinite health and magicka)

Elder scrolls skyrim lost to the ages