iphone 6 battery wont charge

My iphone 6 wont turn on just did the ios 11.1 update (the one with the letter i issues) didnt get a change to upgrade to the newest ios 11.2. the battery was drained because i didnt have access to a charger. when plugged into computer or car the apple logo keeps flashing. .will not completely turn on... tried to hold down lock and home button but the screen still just flashes the logo. battery was fine before that ios11 update