Another quality Patrol question coming up lol

Before I take it to our local mechanic I want to have one last crack at trying to fix Lachys quad bike.

4 stroke Yamaha YFZ50 quad bike, fairly newish.

He rides it a lot but the other day it just stopped and I won't start again.

I noticed a heap of fuel coming out of the carby drain hoses too when it stopped.

It looked low on fuel so I topped it up and it never ran again, electric start, engine cranks but no firing.

Air filter all good.

So fuel was coming out of the carby drain pipe when it stopped running but doesn't do it anymore.

Checked spark, and even replaced spark plug.

Drained the carby, etc and still no joy.

Fuel is on and flowing through carby.

The fuel is fresh and not contaminated as i used the same jerry can in my ride on mower and that's been running fine.

I'm assuming something has gone wrong with the carby, like the float stuck open, but I'm not a petrol guy and not overly confident in pulling apart a carby.

Is there anything else I can try or do all the signs point to something wrong with the carby?