Service [Q] Xperia Arc S is not starting up

Hello friends I just bought Sony Xperia Arc S (LT18i) from eBay after 12 days of using it stopped working

I was using mobile in morning mobile was full charged and after some time it was off I try starting it but it was not starting I look over XDA and tried every thing still no result when I connect it to pc the green led stay on but when I connect it to adapter green light constantly blinks
I tried flashing it using flashtool with original firmware but phone keeps on disconnecting so installation gets aborted.Phone is not even showing Sony logo.

1 My phone is not rooted
2 It is not upgraded to ICS
3 I tried everything single thing like taking battery out and holding power button, volume up and power everything
4 Phone is not under warranty

Please confirm me this is not an hardware issue and how to solve it
Thank you everybody for reading it.