Not very likely. AFAIK pilots don't manually enter the waypoints, coordinates, etc., by themselves but data already preloaded, we had in special 8-track mag tape, now maybe in special disk or uploaded.
This MH370 lost in the night sky is out of ordinary:
ATC transponder was turned off (like the 9-11 hijackers did, you'd be flying as UFO without squaking)
ADS-B stopped transmitting
Subang ATC couldn't contact the plane but a Narita-bound 777 pilots got them on radio (VHF?) whoever in the other end didn't sound like neither MH370 pilots.
Families saw some passengers' smartphones online on Tecent QQ, how on earth could that be?
"AFAIK"is exactly correct. As far as you know.
Rest your heart and mind, its no longer an 8 track mag tape. Yes, many companies (not all) have pre loaded routes. Any number of circumstances on a regular basis changes routing. SIDs, STARs, traffic, restricted airspace, blah blah blah. Pretty much routine "stuff"
"Flying as UFO without squawking."
If you have been previously identified, you are not exactly an UFO. You just not squawking detailed information such as your altitude. When a flight crew realize they may have busted an altitude, investigation shows in many cases, they instinctively turn off the transponder. Not unusual.
Yes the hijackers of 9/11 turned off the transponder in 3 of the 4 aircraft. So now anytime a transponder is turned off, you are going to conclude it was a hijacking? Wow.
"ADS-B turned off"
Who really knows and more importantly who really cares. I can think at least a dozen or more times last year, pilots forgot to turn it on. Has no meaning in this specific moment
"Narita bound pilot got them on radio"
That report turned out to be false. Once again, more than half of what you read in the media is full of crap, half truths and lies
"Mobil phones online"
Most Asians here believe in ghosts. So if that floats your boat and make you want to believe that a land shark came up and bit them, have at it. Enjoy