Re: Priority: Geth Dreadnought will not start
What Mods do you use?
Realistically, this is most probably a problem with a Mod or the game files being corrupted.
Both can only be repaired if you vanilla the game by repairing it or by uninstalling/disabling them with "ME3Tweaks Mod Manager".
Repairing is still the saver option though.
Repair:
(Origin: Game Library > Right-click the game cover > Repair)
(EA app: My Collection > Click on the three dots on the game cover > Repair)
(Steam: Game Library > Right-click the game > Properties > Local Files > Verify integrity of game files.)
You can reinstall the Mods once you are in the mission to see if the game still works, if not, one of your Mods is the culprit.