I finally managed to charge the battery. The betterie would no longer charge simply by placing the box on the docking station. After several tries, it seems that this works: put the box on the charging station, switch it on and leave it running like that... it charges again.

Hello, I had the same problem. Finally I sent it back. The shop told me that there had been a lot of defects on the red and green ones. I will try another colour 🫣

I bought them from Amazon and have no problems