I have opened many lithium batteries, but not this one. Shouldn't be too difficult for someone with proper tools and experience to replace the raw battery pack (being careful with the embedded circuitry) if the plastic enclosure can be opened without damaging it.
For those that aren't aware, many of these batteries, including those that run power tools such as drills, impact wrenches, and the like, have circuitry in them which will prevent them from being recharged if the battery has been drained to too low a level. Note, I have no idea if this is the case with the Leica batteries...
I've restored some of these to working order by opening up the battery, bypassing the circuitry from the raw battery pack, and charging the battery pack directly (wired charger with alligator clips.) Once the battery pack reaches a minimum charge threshold, the circuitry will then allow the pack to be recharged again using the standard charger, so it can be reassembled and used normally.
Note that often the manufacturers will use tamper-evident screws to assemble...so opening it up will of course void any warranty.
Moral of the story, if your lithium powered drill/leaf blower/chain saw, etc. uses one of these 'smart' batteries, and the battery 'appears' to be dead, it may not actually be! You might be able to resurrect it. There are youtube vids that show how.
Some may have thoughts about manufacturers that embed circuitry that forces users to buy new batteries even if the raw battery pack itself is in perfectly good rechargeable condition. Even if it's not able to get to 100% 'new' capacity, it can still be very usable.