Restarting in download mode is usually a stuck power button, try giving it a wiggle before you insert the battery.
Flash a full stock rom with odin, then boot straight into recovery and factory reset. Look for any error messages in recovery.
Note: This quote doesn't automatically apply to everyone, decide for yourself if it might apply to you.
Originally Posted by justruss
What has this place become?
It's essentially a few people graciously answering the same repeating of immature, lazy, demanding questions from the masses.
Nobody searches. Nobody reads the first posts or titles of threads. Nobody even looks at posts a couple above their own.