Montblanc MB01 - Battery Replacement

I'm trying to replace the battery in a pair of Montblanc MB 01 over-ear ANC headphones (2020, discontinued). The cell is dead — about one hour of runtime against a rated 20, and it collapses from 75% to zero in one step. Montblanc no longer repairs them and won't supply parts. There is no teardown, guide or forum thread for this model anywhere I can find, including in Chinese, Japanese and Korean.

I've been careful and stopped rather than force anything. Here's what I've established.

Ear pad side (right cup). The pad comes off cleanly — it has its own plastic carrier ring that clips into the housing, no adhesive. Underneath is a black bezel carrying the regulatory markings: Model MB 01, Montblanc-Simplo GmbH, Made in China, INPUT 5Vdc 0.72A, FCC ID 2AENP-MB01, IC 20163-MB01, CMIIT ID 2019DJ11415. Around the bezel perimeter are eight or so openings, all identical rounded rectangles, evenly spaced — as far as I can tell these are all sockets for the pad's clips. I can find no screw heads anywhere on this face, including under raking light. Inside the bezel is the driver behind a fabric dust cover. The only central feature I can feel through the fabric is the driver's dome, so nothing structural there.

Outer face. A smooth silicone dome with the Montblanc emblem. No seam, no lip, no step I can feel with a fingernail anywhere around its edge. There's a pinhole mic port through the silicone itself, which suggests it's bonded and registered to a mic capsule behind it rather than being a removable cover.

Chrome band. Carries the buttons, USB-C, 3.5mm jack and another mic port. I tried gentle leverage here with a plastic pick and the metal deformed very slightly before anything released, so I stopped immediately.

So: no fasteners visible on any of the three surfaces, no seam that takes a pick, and thin polished trim that bends before it gives.

My questions:

1. Has anyone here ever opened one of these? Even a partial attempt, or a failed one, would be useful — I've found nothing at all online, and I'd rather learn from someone else's dead end than repeat it.
2. Does anyone recognise this chassis? The build is almost certainly ODM, so the same shell may exist under another brand with a documented teardown.
3. Is a bonded outer cup the likely construction here, and if so is this a heat-and-adhesive-cutter job rather than a pry job?
4. Am I missing an access route — under the yoke fitting, or through the headband attachment?

Thanks in advance to the community for the help! Those are not perfect but they feel super nice I would like to keep using them wirelessly.

Thanks, that's really helpful — and good to hear the driver side is still the likely route. Photos below.

1 — Driver and dust cover, close. The fabric across the acoustic opening with the printed R ring. One of the perimeter openings is visible at the edge for scale. (Serial number blanked.)

2 — Bezel edge and chrome band. Shows the relationship between the black bezel, the pale ring around it, and the polished band. The small oval in the chrome is a mic port.

3 — Bezel at a shallow angle. Best view of how the black bezel sits relative to the pale ring and the outer shell, and of the openings in profile.

4 — Bezel, full view. Regulatory markings, and four or five of the perimeter openings visible at once. This is the face where I can't find any screw heads — these openings are what I've been reading as pad clip sockets, all identical and evenly spaced.

5 — Outer face and chrome band. The silicone dome with no seam or lip I can detect, and the band carrying the buttons, USB-C and jack. Leverage here made the metal flex slightly, so I stopped.

Two additional points: The dust cover isn't moulded into the baffle — the fabric is soft and moves under a light touch. And looking at how it meets the black ring, it appears to be glued and sandwiched between that ring and the assembly underneath, with the ring trapping its outer edge.

If that's right, the black ring is a separate part rather than part of the housing, which would make it the way in.

Questions:

Does that read correctly to you — is the black ring a removable retaining piece with the dust cover captured under it?

If so, is it clipped from behind, glued, or both, and where would you start? I'd rather not lever blind with the diaphragm sitting right there.

Are all those perimeter openings really just pad clips, or have I misread one of them as a clip socket when it's actually a fastener well?

Happy to take more shots or measurements of anything specific.