Check the main fuse again.
And you're sure your friends battery was good and the right size to start the bike?
Sounds like a bad battery still. Once it's dead, it's dead.
Get a battery, charge it, and install it, make sure the big main fuse is good, and then fire it up.

 

he took the battery out of his working 2012 KLX250s.

Where is the main fuse?

 

Under the seat. It's bigger than the rest and by itself (it's a normal size bladed fuse, the others are small ones).

 

Check your grounds
I am going through a similar thing
I believe it is my battery

 

I'll look tonight for the main fuse.

113moro - keep us updated.

 

How about the alternator or voltage regulator?

 

Good question, surferdude. I'm not familiar with how to diagnose or troubleshoot them. Any ideas?

 

Ignition switch?

 

If his headlight is not working, the regulator/alternator will be way down on the list at this point.

With the nic "surferdude", probably should just think about it a bit?

 

michaelb2, do you have the owners' manual? It shows the fuse locations. There was a post recently that mentioned the owners manual is a free download from Kawi.