The activation of this (amber yellow) "warning" indicates that the hands free system has detected that the battery that permits the active key (1, fig. 62) To communicate and turn the vehicle on is almost discharged.
Note
In this case, ducati recommends replacing the battery as soon as possible as described in the paragraph "replacing the active key battery" (page 88).

Hands free key (hf) not recognised
High engine coolant temperatureTrip 1 meter
This function shows the distance travelled since the trip meter was last
reset (in km or miles depending on the specific
application).
Press and hold (1) "s" for 3 seconds while in this function to reset the trip
odometer.
When the reading exceeds 9999.9, Distance travelled is reset and t ...
Reassembly of the crankcase halves
The crankcase halves must be in good condition and perfectly clean. The
mating surfaces must be perfectly flat and free
from burrs.
Overhauling the alternator-side crankcase half
The following parts must be present on the internal side of the crankcase
half:
Gearbox secondary shaft bearin ...
Hands free system key-on and key-off
Key-on consists in turning on the hands free system and all
of its electronic devices.
Key-off consists in turning off the hands free system and all
electronic devices, and makes sure the engine is turned off.
Key-on is done using the button (6) on the handlebar on the
right switch or using ...