Furuno NX-300 Navtex problems

[CSY Man]

This unit has worked for years with no problems but recently starting acting up like an old a Windows PC:
Not responding, freezing up, grey screen, etc.
Removing power and waiting 30 seconds will get it going again, until next time.

It probably needs a software update, or master re-set or something.
Contacted Furuno USA and they are happy to look at it: $100 evaluation fee plus shipping both ways.

Anybody with the same unit know how to do a reset, like pushing 2-3 buttons at the same time, or something...?