5 speed YJ won't start. No clicks. Pop started and drove just fine for about 5 minutes and still doesn't start. All the lights and everything work, when I turn the key, the brake light comes on in the dash.
If it is not turning over try rapping on the starter with a hammer to free up the brushes. Not hard, just a good tap to vibrate the brushes. Mine just did the same thing. The brushes may need replacing.
While its running I can turn the key for a second and get that grinding sound. So it's not the starter. And I get the check engine light when turning the key to power. Let it charge for 20 minutes and I still get nothing.
I agree with testing the battery and alternator then.
Sounds like you don't have enough power on start-up. Hopefully the alternator is fine since the engine runs ok with the bump start (may still be bad though). First, you can just pull the battery out and take it to autozone. Have them charge it and test if for free.