At last, I got it fixed folks. Thanks for everyone's guidance. Here is what I did.
1. Flashed the boot.img from the OTA Update for 3.63.708.3 found on HTC1GURU.COM
2. Downloaded Hasoon2000's HTC One All-In-One Toolkit
3. Executed Perm Root from the Toolkit as my SuperSU was missing
4. Executed ADB Sideload a ROM with CM 10.2.0-m7ul
vola!!!! your phone is alive now
few points to note here - when I tired to execute the ADB Sideload I got an error
skipping MD5 check : no MD5 file found
assert failed: getprop("ro.product.device") == "
E: Error executing updater binary in zip '/sdcard
E: Error installing zip file.......
this post saved my life.
I just removed assert device statement (first few lines from the update-script file) and all worked fine.
Again - Thanks everyone