Open the camera, see if the green/red light is on, the with your eye still looking through the window, as it begins to appear, slowly slide the clamshell closed.
If the switch is working, the light will go off,
To confirm, slowly open the camera shell and after a few mm to a cm, the light should come on.
Leaving the clamshell open means the battery will be on and drain, its as simple as that.
This camera was designed for silver oxide batteries, so ditch your alkalines and get a fresh pair of SR44's
In case you need them, this link will give you both user manuals, short then long, in the same PDA.
Please consider making a donation to the site.
https://www.butkus.org/chinon/olympus/olympus_xa/olympus_xa.htm
Good Luck.