SRM Origin (MTB) disassembly?

[shinkansen]

I have an SRM Origin (MTB version) with external charging port, but it only holds charge for a few hours vs. the claimed 100+... SRM support have gone silent on me so I'd like to fix it myself. I've opened up wired and wireless SRM's with no charging port but can't see how to get into the MTB version. If I remove the carbon crank arm there's a lockring (the teeth of my tool are not long enough to reach it). Does anyone know if removing that lockring is how you get the cover off?

[RyanH]

I know some of the PM7 versions are done from the externally facing side on the edge. You'll have to grab a razor and see if you can feel a gap.

[Gorian]

I'm trying to open MTB SRM PM6 now and looks like it's completely filled with liquid plastic. Wondering what to do to change the battery. Not so easy as with road bike version