My iphone freezes after restart

Dear Sir

My iphone 6 has a software problem: after a previous update, When the battery empty or if I restart, or if I make airoplane mode then try to get back, it asks for the passcode, go to the cover page and freeze, If I restart it again, make the same, it doesn't work properly except when I leave it for sometimes (may reach 5 minutes or even more), it wakes up and work

That is why I got panic when the battery is 4-5%

This number appeared on my screen when I entered a code, if this may help: 354407068675460