I have the G1000 version 1.02 bios version 1.03.
When using a floppy to upgrade to the newest version bios (downloaded from a Roland site),
the G1000 complains "Read Error" then nothing happens.
At the next power-on, G1000's LCD keeps flashing between full screen dark and full screen white.
I could not find any note about restoring the factory reset of the bios (different from restoring factory patch setting).
Cannot find any relevant information on official Roland sites (US, UK, Canada, France, Japan).
I did send an email to Roland US and Roland Canada (Saturday), I do not know when they would reply with a solution.
Please post the solution if you know how to solve it.
Many Many Thanks.

It really looks as if you have corrupted the (OS) Operating System.
I Suggest you you download the OS again and format a different floppy on the G1000 before putting the downloaded OS onto it and try another install.

Graham UK