Batch didn't ferment all the way out. What to do?

After too long of a break, I am finally able to brew again. I recently brewed a Belgian Chocolate Stout, using the Belgian Abbey yeast, which I have had very good success with in the past, that stopped fermenting at 1.040. I have tried rousing the yeast, pitching a dry yeast on top of the beer, and nothing worked.
What do I do with this beer?? I can't imagine bottling it as it is.

How does it taste? If it tastes good, or even pretty good, I'd bottle it. It might not be what you were hoping for, but it's probably as good as it will get. You can always try and brew it again.

It's difficult to add more yeast at this stage because you can't oxygenate the beer for the new yeast without oxygenating the beer. Some people add beano to their beer when the fermentation is stuck. That could work to lower the gravity, but I've never fooled with that, and it won't necessarily make the beer taste better.

Some questions to help troubleshoot:
1. What was the starting gravity?
2. Did you use a starter? How much yeast did you pitch?
3. Did you oxygenate? How and for how long?
4. How long has the beer been fermenting?
5. What temperature did you ferment at?