Welcome to the forum. After the Battery has been Charged and load Checked to make sure it is good.Check some of these areas/ Bike is in Neutral and Neutral light in on.Clutch switch on the Clutch Lever is good.
Some older model years of Bikes 2003 and 2004XBs had KickStand Switches(when)down and put in gear or malfunctions will not start.The Start Button is working properly(contacts may need cleaning)or replaced. Key Switch is not wobbly(probably not)that.Never jump start or leave the Cables on the Bikes Battery from a running Vehicle,especially a Diesel,trying to charge the battery up to start it.
Relays are good and Fuses are good or not Loose.Grounds are snug in all areas.
Finally the Starter may be the problem but check all first to make sure. A Small spritz of W/D 40 in the Start Button ONLY- let it sit a minute will clean the contacts.
Do not use wd/40 in any other area of the Electrical system.This should get you started in the right direction.If the starter turns out to be just stuck you can GENTLY tap on the Right side of it at the silnoid to un stick it but I wouldn't go riding if it turns out to be that, till replaced. Hope it is something easy to fix.*Jimi