Re: Notification bar freezing
Extract as follows from full article here might be of some help :-
What to Do When Your Android Phone or Tablet Won’t Turn On
Like other operating systems, Android can sometimes hard-freeze and refuse to respond. If Android is completely frozen, your device may be powered on and running — but the screen won’t turn on because the operating system is frozen and not responding to button presses.
You’ll need to perform a “hard reset,” also known as a “power cycle,” to fix these types of freezes. This cuts the power to your phone or tablet entirely, forcing it to shut down and boot back up.
On a phone or tablet with a removable battery, you can remove the battery, wait about ten seconds, and then plug the battery back in and boot it up.
On a phone or tablet without a removable battery — that includes most modern Android devices — you’ll need to long-press the Power button. Press your device’s Power button and hold it down. You should only have to hold the Power button down for ten seconds, but you may have to hold it down for thirty seconds or longer. This will cut the power to your phone or tablet and force it to boot back up, fixing any hard freezes.
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