This means that the fitbit has got into a confused state.
It needs to be rebooted as follows:
http://help.fitbit.com/articles/en_US/Help_article/1186
Plug into the charging cable with a power source (PC or mains).
Hold down the button for about 20s
It should then restart. This should not clear the data on the device.
However it may not have counted steps during the crash.
Developer Rants 