Many apps not working, out of troubleshooting options, what's next?

[AC Question]

I have a Samsung Galaxy S4 model SGH-M919 / Android 4.4.4
It recently started having a lot of problems:

The camera does not work. When I open the camera app, I see the app buttons and icons but none of them work. I see a black screen where the camera view should be. Then after a minute or so it says "Camera failed."

Google Play consistently fails with "Unfortunately, Google Play Store has stopped"
Some other apps do this as well.

When I try making a phone call, the screen goes black except for the status bar at top of phone, I eventually see "Activity Phone isn't responding. Do you want to close it?"

I sometimes see "Process system isn't responding".

Many other apps work just fine but everything feels very sluggish.

When I press the volume up or down buttons, it takes a couple of minutes for the display to show the volume graphic, if at all.

----

I tried the recommended troubleshooting steps of "clear cache" and "clear data" for the failing apps - no change.

I did a clear system cache (via the home, volume up and power buttons) - no change

I've taken the battery out and left it out overnight before putting it back in - no change.

Suspecting the camera was having a hardware problem and affecting other things, replaced the rear camera with a new one - no change.

I did a factory reset - no change.

I re-flashed the stock ROM via Odin - no change.

Is there anything else I can possibly try, or is it time for a new phone?

 

[Tim1954]

Back it up while you still can and replace the beastie....

 

[QuietPlanet]

Original poster here. (Forgot to log in on original post).

Wondering if it's worth taking this phone someplace for possible repair, or if that might cost more than a new (refurbished) phone?

 

[Tim1954]

No harm in trying. The sofware is outdated and is no longer supported, so you'll still have an older device. Here (Australia) Samsung has popup stores in big shopping centres where they have expert Samsung ppl who can help you with this kind of stuff... They update sw and do all that goodness. Maybe if they reflash the sw the device might behave once again...