Fujitsu FI-6010N Operator's Manual page 208

HINT
5. Press the [OK] button.
The system update process is started.
After the system has updated, the scanner is restarted.
ATTENTION
HINT
172
When installed options or the system including installed options
are updated, the following window appears.
Wait for the system to restart.
During the update, do not press and hold down the startup button
for longer than 4 seconds, as it may cause the scanner to function
abnormally.
The network interface connection will be lost when the scanner is
restarted to complete the system update. To continue with other
settings, wait a short time for the device to restart, then login to the
network interface again.