Phone 5S apple logo blue screen reboot problem how to solve

My iphone 5s at startup apple logo seen and after 20 second seen blue screen and restart. After again apple logo seen and blue screen.....

I didn't raplace my screen so iphone hasn't damage line of mainboard on screen sockets projections screw.


What is my iphone's problem. How can i fix it. Please help me.. ?
Baseband Ic problem..........
change first U2 ic, if not working power ic..
Normaly blue screen is coz of this check out

5S Blue screen and error14 - solution inside!

Sent from my Nexus 5
blue screen and reboot is due to u2 ic if you changed that ic and you still have reboot and blue screen replace U6 ic remember not u6_RF just u6 ic which is eeprom