How can I fight a ASAP failure chapter?

You generally can't. It's up to your command. Technically it rests at the Brigade commander discretion. If you don't have six years of service you can't request a separation board to fight it either.
You'd have to convince your command that you're worth saving and fighting for.

Without knowing more of your story, I have to look at it from the point of view of your command. You made a bad choice and were given the opportunity to continue being a valued member of the team by completing ASAP. You made another bad choice in ASAP and failed to complete. If you go back to your counseling statements you should see that there are consequences to those actions resulting in separation for failure to maintain standards.
You may have a leg to stand on if you were a self-referral. The only recourse you have now is to reach out to your NCO support channel to get in a room with the commander and plead your case.
If you are separated, I think is is characterized as an OTH.

So I'm going to tell you an unspoken, well known secret.....
Chains of Command have a bit of latitude when it comes to whether or not they will actively pursue a chapter. First instinct is generally not too, because it's a paperwork hassle. It eats a lot of time and effort.
BLUF: If your unit is actively chaptering you, you've been identified as a burden, and you need to go. If you fight and stay, be prepared for EVERYTHING to go on paper so another chapter can be pursued. BLUF PS: Learn from this and move on. Do some soul searching. Don't burden your unit and the Army in general with your BS. Your leadership is busy enough as it is. They don't need someone who isn't value added.