"for entering in to boot screen,
without pressing any keys (power+vol_down+reset)
Can you try connecting your device to PC using any min USB cable (Not htc extUsb cable, i do not have extusb cable so not sure about that, but this works for me atleast
).
a. follow the steps from (A) to (
E) as mentioned above
b. then connect a
MINI USB cable to cell and connect to PC
c. Do not press any button and check if device automatically switches on and enter into boot screen.
d. If you are lucky and if it enters into bootloader, then try flashing NEW ROM using USB or SD card method"
I tried this and it is letting me install the rom again. I hope it starts working again.