HTC 820 Problem

good evening
i have htc 820 with this informations
*** Software status: Modified ***
*** Unlocked ***
A51_UL PVT SHIP S-ON
HBOOT-3.19.0.0000
RADIO-01.01.010_U10305041_08.01.50512
OS-2.10.410.4
eMMC-boot 2048MB 0C
Nov 13 2015,18:02:23.0
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WAS RUNNING ON ANDROID 5.0.1
got message to update to android 6.0.1 size: 613MB
when the installation started and device restarted it went to twrp and gave me message saying : no os installed! are you sure you wish to reboot?
now the mobile is not working and i tried to flash rom twrp and stock recovery
and also tried this guide
http://ift.tt/1sFIzry
and tried some roms to boot the phone but nothing is working
now the phone is dead and stuck on htc logo
can someone help me to get the phone back to work ?


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