Thank you very very much for all the time you spent helping me.
It is now working. I think what did the trick was to uninstall the arduino com4 item, unplug and then re-plug the arduino board.
You are the best.
Jim
Now some nagging. When posting code or error messages, in future please use code tags. If you click the <CODE/> button, it will create a ready to fill in block that looks like below
```
type or paste code here
```
Replace the text with your code or error message; make sure the three back ticks are on their own line. It makes it easier to read and copy and the forum software will display it correctly.
E.g. your upload output from post #17 will than look like
C:\Users\techn\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino17/bin/avrdude -CC:\Users\techn\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino17/etc/avrdude.conf -v -patmega2560 -cwiring -PCOM4 -b115200 -D -Uflash:w:C:\Users\techn\AppData\Local\Temp\arduino_build_373519/MyBlink.ino.hex:i
avrdude: Version 6.3-20190619
Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
Copyright (c) 2007-2014 Joerg Wunsch
System wide configuration file is "C:\Users\techn\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino17/etc/avrdude.conf"
Using Port : COM4
Using Programmer : wiring
Overriding Baud Rate : 115200
An error occurred while uploading the sketch
This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.