To change the keyboard language from Chinese, or any language, touch the option on the right of the 'Enter' button which is located on the bottom right corner of the key board. If your phone's operation language is not in English, press the 'Applications' button which looks like a 4 by 4 grid of grey squares. The find and select the 'Options' application which looks like a mechanical gear with a green rim. At the top of the options screen, there is a row of 4 option sub-categories and select the one that has looks like a the outline of a phone. The option with the letter 'A' is the language selection option. Touch that option and select the English language or the language you prefer.
Putting the back panel on your device works in the opposite way as you did taking the back panel off. Start by pressing in the bottom sides of the back panel onto the phone and continue up the phone until you have completely attached the back panel onto the phone. Note: If you used a replacement guide that required you to take the power button off, make sure you place the power button on BEFORE adding the motherboard (following the guide backwards). Not doing so will result in you not being able to fully close the back panel due to the power button not being placed where it needs to be.