[HALP] HARD bricked!?

I have a rooted and xposed 820. And on this morning, while I am using my phone to play Pokemon Go, the phone got itself shutted down all of a sudden ( black screen ). And several seconds later it boots up, showing the green "hTC" logo alongside the red words below, and again, several seconds later ALL THE WORDS on the boot screen turned yellow and a second later the screen turned off and it reboots again! This loop has run for 4 times and in the last time I decided to go into TWRP to clear cache and davik cache and hope this will bring it back to life. Well it does make it booting into the system and showing the bootanimation, but in some seconds, it reboot again and the yellow words appear again.

After the last yellow screen appeared I was frustrated and decided to leave it shutted down ( TWRP method ) and try to fire it up later today. Later, I dissemble my phone and reseat the battery, hoping that this will reset some of the parameters inside the phone. But, just when I want to power it up after that, I found that it can be neither power up nor enter recovery. After connecting it to my adb and fastboot-installed desktop computer, it blinks orange LED lights and it CANNOT BE RECOGNIZED AS A DEVICE by my computer in device manager.

Now I am not sure if it is really hard bricked or just any other thing else:confused:

@tomal @vuk1963 @QkiZMR