2008 WR250R won't start

Rolled the bike out to ride to work the other morning, (after not starting or running the bike for about 5 days) started it and it ran for about 15 seconds then died. I hit the start button again and got a very slow crank and it would not start. So my first thought was battery. It is the original battery. I put it on a 36 hour trickle charge and tried it again, only I kept trying to start it until it would not crank at all and then just got a buzzing sound. The battery reads 12.69 volts, which I thought would be enough. When the key is put in the start position I hear the fuel pump priming and all of the lights work. The clock is not the right time. I replaced the plug, in case I fouled it with the slow cranking, but it still does not start. Any suggestions?
Thanks

New battery, it sounds like.

Try this <-- last resort

Can't say it enough - do not  start the car during jumping.

I have the exact same problem on my Yamaha WR250R 08. I bought a new battery and I have replaced the spark plug.
But still the same. I don't know what it is. So I think I just have to bring it to the store and get the mechanics there
to look over it.

click me <-- also worth a look

I don't think its an electrical problem, the lights goes on, the fuel pump buzzing and the bike is cranking when I press the start button.
But there it stops, I can crank the battery empty if I want to, but it won't start..

Bad fuel
Clogged fuel line
Pinched fuel line
Clogged air filter
Wrong size gap in spark plug
Loose wire on battery terminal

??????????????

Air, fuel, spark - then compression.   

I have thought about the fuel. So I removed the tank and emptied it. Need to fill it up tomorrow.
The fuel line looks okay if I'm not mistaking. I bought the exact same spark plug as the original. NGK CR9EK.
Just changed the battery so I think the wires are okay. But I can check that to.

So the problem was the battery, put in a new Shorai battery and everything is starting and running well.
Thanks for all of the suggestions, info, etc.