Edgar: I really feel for you as you have a premium, high end e-mountain bike that is rendered useless without a battery. I often wonder if this is the fate for all of us as high end manufacturers like Yamaha and Bosch leave early ebikers hanging out to dry when they discontinue motors, batterys and switch gear for our older ebikes.
For the heck of it, like you, I checked. And checked. Ebay USA, Germany, UK and Spain. Nothing. Craigslist: nothing. Though I am not on facebook, I can log into Facebook Marketplace for regions/areas around the country and in GA I found a Brose powered Atom commuting bike with the internal battery. A shade over 2200 dollars. You might be faced with the only remedy being to find an Atom Pro X and purchasing it for the ebike drive system and battery if you wish to keep what I percieve as a very little used ebike, going off the picture you've shown.
The only other alternative to buying an entire bike for parts, is to contact Brose and see what they have to say in trying to provide any kind of help for you. A shot in the dark it is, as you stated, BH tailors it's bike using components from that battery manufacturer in Taiwan and Brose, the engine manufacturer in Germany.
Specialized and Bulls also power their bikes with Brose, so worth a shot to shoot them an email too. I mean, at this point, you may have to Frankenstein that BH using a Brose drive system from another brand.
I know that up to last summer, Voltaire Cycles out of Verona, NJ had all kinds of parts and batteries for BH ebikes (I was in the market for another Yamaha 500wh battery and found their site). They have since cut down their supply. But maybe give them a call or email as well. Good luck, I feel for ya and let us know how this plays out for you.
