Olympus XA diagnostic help

Just got a used olympus XA but it has a peculiar problem that I couldn't immediately find an answer for online so maybe somebody with more knowledge on these little camera's can help me find the culprit.

So it has new silver oxide batteries.
But when try to take a frame, on almost every shot the camera doesn't fire. Usually after opening and closing the lens cover a couple of times it does fire. So maybe it has to do with the camera not sensing that it is open.

But I just noticed that I can also take the frame by putting the lever on the battery check: The Battery check tone works normally when closed or opened without the film advanced and ready to fire. However, when the camera is open with a shot ready to fire, the battery check tone doesn't work and the camera can't fire. But when I then turn the lever further to the self-timer and then return it to the battery check tone it will beep and somehow I can always take a frame then.

What could the culprit here? Thanks in advance.