SureAI

I have Yeros key, and the Secrets quest has started.

When I try to open Yeros Tower, I get a popup that says "You Shall not PASS".

How do I get into Yeros Tower?

Hello
To see what exactly your problem is a Savegame would be very helpful, please upload it here.
They're found in ...\Documents\My Games\Enderal\Saves
We'll need the *.ess and the *.skse file, pack both to a zip or rar archive (the forum doesn't accept *.skse directly).

If you mean the outer door of the tower, you need to pick the lock, the key is used inside.

Which is very likely that you either play with the old Enderal version or use an old Savegame (befor ForgottenStories, 1.5.0.0).
There is no support for the old version anymore and old savegames are not compatible with Enderal-ForgottenStories.
Current is the Enderal-Steam-version 1.5.8.0.

Door is unlocked.

Is there no way to advance using setstage or other console command?

We don't know what exactly your problem is, but you probably have the old version of Enderal or at least an old savegame.
We haven't gotten a save from you yet either, to be clear.

If you have the old Enderal version, there is nothing there.
If you have an old save, it's not compatible with the current Enderal-ForgottenStories and therefore you won't get anywhere. The console will not help you there.

either you play the old version of Enderal as it is
or you install the current version Enderal-FS of Steam and start a new game.
But if it is from the current game, we need a savegame for testing.

How do I know what version I have?

The updater says I am up to date.

Also, is it normal for the game to crash often?

What is the quest ID for Secrets?

So, it's sounds like you use the old (= non-steam) version of Enderal. It's neither supported anymore (for just about two years already) and it doesn't really contain the quest you're trying to play. It doesn't go further than the door in your version.

If you want to play on a more stable version with more content, download Enderal from Steam. As others previously said your current saves won't be compatible with the steam version.

Ok, but I just downloaded this version last December.

As far as containing the 'Secrets' quest, if the game did not contain the quest, why would the quest start when I got the key?

Again, how do I find the version of Enderal that I have installed?

We asked multiple times already: did you download Enderal via Steam or from somewhere else? That's how we know, what version you're on.

If you downloaded it from Steam and this happens, then I want to have a look at your save (which was also requested multiple times already).