- Check the fuses.
- Fuel pump is running when you put the bike on contact?
- Try to hear if there's a click somewhere in the bike when you push the start button. If there isn't, it might be the start relais. If there is, the starter motor might be the problem. Could be a loose contact, dirt or it's just broken.

These are the first things to check

New battery.

New battery would mean you see the headlight drop.
Check the negative cable from the battery, look under the heat shrink insulation and follow it to the frame and also to the starter motor.
Check main fuses and starter relay which is bolted to the battery box.