Replacement battery for Philippe Starck Fossil...

Question

I have a starck negative display watch with rubber strap (don't know model number). A jeweler tried replacing
the batteries but also said they couldn't be replaced and just gave the
watch back to me.

Now, a few months later, I've now opened the watch to find that the
jeweler didn't leave the old batteries in the watch! I've referred to
the manual, and that doesn't state which model batteries to use when
replacing them.

Can anyone help?