Also make sure you don't have any ZIP files in the root of your internal sdcard.
Red exclamation mark usually caused by:
1. Corrupted download file (re download)
2. Incorrect file name (make sure the download file from Asus website is unzip, the second zip file rename to EP201_768_SDUPDATE.zip
3. Extra zip files in the root directory (delete all the zip file in internal or external root directory of SD card)
4. corrupted external sd card (if you use external sdcard, just reformat with fat32).
5. Frozen system apps/modified properties file.(unfreeze sall system apps and restore original properties file)