System UI has always stopped
first of all, sorry for my poor English because im from China.
i came here for help.my S5 model is SM-G9006W, a China Unicom version. and last week i update my phone via OTA to Marshmallow, then my phone can't work. when i boot up the phone there's no icon but only the wallpaper. and i tried a lot times, then just found the problem the phone may had: when i switched from emergency mode to normal mode, it had few seconds that it could display icons, soon it showed "System UI has stopped"in Chinese. And again and again, always the same pop-ups. Also it made the phone very hot, the battery drains quickly. i switched into the safe mode, the problem was still there. and i wiped the system cache, the problem remained. Since i had no chance to backup my phone, so i feel depressed and don't know what to do and how to do now, i have no idea how to fix it, or just let me have a chance to backup my data at least. the official version removed all the Google Apps at the beginning, so it had no Google Play or Google Account.
Well thanks everyone who read this, please help me if you know how to fix it.