Why doesn't my Lumia 820 start up?

[msafe]

HELP!! my lumia 820 doesnt start up..

please read my short story that caused me serious damage so far:

i had the latest developer preview update up until last week when microsoft announced that more lumias will be able to get the windows 10 tech preview.
i installed the insider and signed up and got ready to get the update
during installing (gear screen ) it restarted and came up with an error "0x803...sth"
i assumed it was because of short storage on my phone.
so i decided to hard reset so that every thing will be erased. i did..
after that unfortunately the insider app crashed when i decided to enroll for fast insider again and when tapping on the magnifier icon it exited.. so windows 10 got cancelled..

after one day my phone came up with a new update massage.. details: "additional language support"
i downloaded it when i was trying to install it (in gear screen) it showed ":-(" massage on screen and it shut down the phone!!!

now it wont start up and every time i try to turn it on the same will happen over and over..

now i'm stuck because i've already tried to hard reset it with physical buttons but wont work since it goes to gear screen and shuts down after 10 seconds..
my battery is full and i'm out of options...

any idea??!

 

[Mohamed Ashid]

You should try using the Windows Phone Recovery tool.

Follow this link to find out how to download and use the tool:
https://forums.windowscentral.com/e...singleTopic%26topic%3DFA142987&token=qTMAmLQv

About the error: It is the bug of The Windows Insider app and occurs when the system space on your phone is low. The most effective way to fix this using the Recovery tool
Next time before installing the Windows 10 TP , go to the about section of windows insider app and check if the system memory is at least 300 Mb .

Have a good day!