ec390uv update instructions

1. Check the serial number underneath the machine... (must begin with 2023....)
2. Copy the update file (390_EUR.....05c) onto a blank (FAT32 formatted) USB stick.
3. With the machine powered off, insert the USB stick into the port at the back of the ec390uv
4. Power on the machine.
5. Machine will display a progress indicator whilst installing update.
6. Once prompted, turn off the machine, remove the USB stick, and power machine back on.
7. Test for correct operation. Done.
