Who likes to venture on a tele-diagnosis?

[Mitica100]

Yes! I have. I followed all your advice. Put on the original kit lens before I entered the shop to get the new batteries.

Hmm... I'm running out of options here...:scratch: :scratch:

I would definitely do what ThatCameraThingy suggested. Take lens off, trigger and see if mirror still sticks, check for damaged shutter blades. You'll ruin some frames but that's a small price...

While checking the shutter blades also check for the condition of the mirror. See if it's deformed in any way, and I'm talking about the metal or plastic mirror holder that flips it up and down. Also, check for mirror damper degradation, it's the thin strip of foam that the mirror hits when it flips up. That foam might be old enough to be sticky and hold your mirror.

I'm sure this has been mentioned (too lazy to look in the thread...) but is your camera (stuck) on self-timer? Or does it have a "T" setting?

 

[Mitica100]

PS Can you take a picture of the mirror (lens off) so we can see the innards that way?

 

[LaFoto]

I did, Hanno. Thank you.
I am sure nothing is wrong with the mechanics of the camera. It worked just fine until I had to change the batteries.
All I am worried about now is that we worsened things, my son and I, when we - really carefully! and nothing moved or fell off or whatever! - opened the bottom and blowed the dust off with a soft blow (dry, compressed air).
Keep in mind the mirror did not stay locked.
It jumped back upon a second tiny push on the release button.
Afterwards I could hear the motor wind the film.
Then the battery sign said "Empty".
I opened the compartment ever so little, shut it, and the battery sign said "Full".
Everything looked like normal again.

All that was BEFORE we opened it to clean it.
Ever since, I can't push the shutter release any more - or rather: all I get with whatever I do is the sound of the motor running. A short "zzzzzrrrrr". Nothing happens, though. The battery sign is on "empty". Not even blinking (like it still did yesterday).
I switch it on, I get the zzzzrrrr.
I press the button to change the lense: I get the zzzzzrrrr.
I push the shutter release: I get the zzzzzrrrr.

Old set of batteries - new set of batteries. Always the same. Only that.

So I still don't think it's a mechanical thing.
It's something to do with the controls or the contacts.
And that is beyond me!
I fear I must send it to Canon Germany...