My 208 is a pre facelift too and the only boot release is a switch in the car. No release on the key.
I recently renewed the springs (look like gas shocks) because although the boot lid released remotely it was pretty heavy to lift... the old 'springs' as MB call them were tired for sure. Once the new ones were fitted the boot still does not open fully on it's own (as expected) but, to the delight of my wife, it's much easier to lift open now.