@ellipsis , yes you can try to press IO0 button (leave pressed) then press and release reset button (while leaving IO0 button pressed) then device should be in bootloader mode and readyr to flash as said @arnaud-r

@Charles Trouvé! Je ne sais pas pourquoi, mais flasher sur FireFox (142.0.1 (aarch64, Raspberry pi) ne marche pas pour moi. Changer sur Chromium (Version 142.0.7444.175) et ca marche. Une fois terminé, Firefox peut gerer, a permiere vue, mais je reste sur Chromum our l'instant. En passant, pour moi, le DNS semble figé sur Amazon US (16.100.251.63), et NTP sur ntp.org... Charles, merci beaucoup pour l'assistance! Tony

@ellipsis Making progress on this, but I should have asked where is the best document or link for installation of Denky 4 with Raspberry Pi? I see many fragments on various sites, but cannot find an up to date document. English or French are fine for me. Thanks again