CLI/GUI devices firmware updater from local file

Download new firmware;
if you use http:https://archive.shelly-tools.de/
you get an url such as http:https://192.168.1.100/ota?url=http:https://archive.shelly-tools.de/version/v1.9.4/SHSW-1.zip; use only the parameter (in this case http:https://archive.shelly-tools.de/version/v1.9.4/SHSW-1.zip) to download the file locally.
Alternatively you can use official archive https://api.shelly.cloud/files/firmware for first generation devices.

Run the following command from terminal:
java -jar shellyscanner-fwupdater-1.x.x.jar <shelly ip> <firmware file>
e.g. C:\Users\Antonio\util\shellyscanner-fwupdater-1.0.0.jar 192.168.1.55 C:\Users\Antonio\Downloads\SHSW-1.zip or just java -jar shellyscanner-fwupdater-1.x.x.jar to use GUI (you can also double click on the jar file)

You get approximately the following messages:
Temporary server now responding at 192.168.1.4:8000
Updating firmware ...
Device response to update command:
{"status":"updating","has_update":false,"new_version":"20221027-091427/v1.12.1-ga9117d3","old_version":"20221027-091427/v1.12.1-ga9117d3"}
Press ctrl^C when firmware update is complete
DO NOT close terminal before

Again: wait until the update process is complete
(use Shelly Scanner to check or http:https://<shelly ip>/shelly from a browser)