Thanks for providing the log. The important part is
C:\Program Files\easy-installer>"C:\Program Files\easy-installer\bin\adb\fastboot" devices 2>&1 | findstr fastboot
'findstr' is not recognized as an internal or external command,
operable program or batch file.
exit value = 255
Something a little similar has been reported in the /e/ forum for a Gigaset device: Easyinstaller stops at unlocking bootloader GS290 - Easy Installer - /e/ community
That topic does not have a solution for Windows. The poster successfully used Linux to install /e/. But that may not be an option for you.
Searching the web I found https://stackoverflow.com/q/10244181/6309275
There it sounds like on some Windows installations the system variables are kind of corrupted. The suggestion I linked to is for some older version of Windows.
For windows 10 here is how to check/change the PATH variable (which seems broken on your system): https://www.addictivetips.com/windows-tips/set-path-environment-variables-in-windows-10/
In case you just want to get the installer running, you can try this “hack”
- in the file manager, open
C:\Windows\system32\ - search for a file called
findstr.exe, right-click it and select “Copy” - open
C:\Program Files\easy-installer\bin\adb\in the file manager - right-click somewhere inside the folder and select “Paste”
And then start the installer again.