The KX2 Utility Send buttons are disabled if you are connected to a Elecraft K3 rather than a KX2. Use the Elecraft K3 Utility to install firmware in your K3.
The Send All New Firmware to KX2 button is enabled only when there is new firmware available to send. All the required firmware files necessary to load the KX2 must be present, and the available firmware revisions must be greater than the installed firmware revisions for the firmware to be considered "new".
The Send All New Firmware to KX2 and Send Checked Items to KX2 buttons are disabled while copying files from Elecraft.
If the button is disabled when newer revisions are shown in the Available column, try clicking Copy new files from Elecraft to copy the required files from the Elecraft server.
If the Send All New Firmware to KX2 button is still disabled, required files may be missing from your Firmware folder. See Missing Files.