AMANDA BYNES WON'T BE CHARGED With a Crime

Amanda Bynes is in for a tough road ahead -- dealing with what looks like a serious mental illness and a conservatorship -- but she's not going to be charged with another crime ... TMZ has learned.

Law enforcement sources tell TMZ ... prosecutors will NOT charge Amanda with trespass, arson or any other criminal offense in connection with Monday's bizarre driveway blaze.  We're told cops and prosecutors view her conduct as non-criminal and rooted in mental illness.  We're told the cops almost immediately decided Amanda needed professional help -- not punishment.

But the troubled star is not out of the woods.  She faces DUI charges in L.A. and reckless endangerment and pot charges in NYC.