Woo!!
Great news!!
My IDE2.3.8 is now blinking LED_BILTIN and sending message to Serial Monitor.
I have followed these steps on a flashed UNO Q:
1. udated board package Ver: 0.55.0 using BOARDS MANAGER under IDE.
2. updated router brdige library Ver: 0.4.1 along with all dependencies using LIBRARY MANAGER under IDE.
Now, I have a healthy UNO Q. I am going to give full concentration to my newly opened thread:
UNO Q: Sharing Knowledge, Tips, and Practical Skills
I cordially invite you to join with your knowledge, tips, and skills and at the same time keep interaction with questions and answers.
Thank you all for the generous guidance.