Problem solved!
So I went around the scooter and replaced the single fuse by the battery, re-connected all electrical sockets to their respective partner, cleaned all the grounds, and still nothing. So I (quadruple) checked the ignition assembly I had replaced just 3 weeks earlier. The only thing out of place was that the red wire's housing had melted slightly, but it was like that when I bought the scooter so I didn't think anything of it. So I re-attached the ignition and voila! It started up just fine. I guess the melted socket didn't allow the red wires to make proper contact, although visually it looked fine
So now I need to replace the current (slightly melted) socket with a new one. Not bad, and easy to do. Yee boy!