Hi Franz, we have third-party replacement batteries for the FP1 in stock, here in Vienna (Linz might have some too). See here: 🇩🇪 Ersatzteile zum Testen/Tauschen/Verschenken/Kaufen (Wien & Umgebung) | Austrian Fairphoners
Maybe you can prolong your FP1’s life just a little bit more. If not, we will be glad to accept the working parts of your FP1 as a donation so that we can help other community members to repair their phones. 