Wat's this part?
 

So the little box just behind the battery. The top comes off too easy, I'm thinking about using a little hot glue to keep it from popping off.
https://cimg1.ibsrv.net/gimg/www.mbw...b8283ea95a.jpg
https://cimg2.ibsrv.net/gimg/www.mbw...d52892f665.jpg

Looks like the altimeter. You mean the box that is labelled Bosch.

Yes. Do you have any idea?

I suppose you can hot glue it back. It is not completely air tight because it is supposed to measure air pressure. I have not inspected mine ever. Never needed to.
Find out where the ambient air comes in and make sure that is not blocked. You can also test it now that you are there. I believe it receive a 5V input from the ECU and that voltage get's divided based on air pressure (altitude) Sort of similar to the AFM pot on the throttle body. There must be a spec somewhere for sea level voltage coming out of the altimeter.

But overall, I see no harm in hot glueing it in 4 corners. Since it comes off I would appreciate if you can take a closeup picture of the inside and post it here. Curious to know what's in there.

- Cheers!

First, make sure you know what the box is for. If it’s the altimeter or another sensor, it's really important that its housing and mount are in good shape for it to work right.