JRC JMR-92 Series Field Service Manual page 760

Note
If you try to press the two buttons at the same time of its
booting up, the MFD application would not start up correctly
because of freeze at the splash screen.
In that case, turn OFF the power by pressing the PWR button
on the TOPU, and then turn ON it again.
3.
Restore dialog appears.
Confirm the contents and click [OK]. Rollback will start and the following message will be
displayed.
Note
If you perform a rollback, Following user data of the latest version will be erased.
Certificate, Connection setting for ISW, Portlist, Personal settings, Route, User
chart, Total distance
Wait for a while until the rollback completes.
Note
This equipment may restart during installation.
5-17 Section 5 Software Update