Install the correct USB drivers for the Xperia L1 so your computer recognizes the device in Flash mode.
Once Flashtool detects the green LED connection, release the volume button.
variant. You can download this directly through the integrated downloader inside Flashtool.
The first boot after flashing a new FTF file can take anywhere from 5 to 10 minutes. Allow the system ample time to rebuilding the internal cache.