Insert the USB drive into the USB port located on the front or back of the NLS3601 decoder.
The NLS3601 is a locked carrier device, not a generic Android box. Most “guides” online are either speculation or for different models. actualizar firmware decodificador cantv nls3601 por usb link
That said, some users in forums (like ForoTelefonía or ForoVinotinto) have attempted unofficial updates using generic or recovery methods. This is not recommended unless you have the exact, signed firmware from CANTV. Insert the USB drive into the USB port