Sorry if it's obvious, but did you try to update the firmware via Chinese language? Most likely you already updated to the latest via English, but sometimes (especially for older models) there are later firmware updates when selecting Chinese language or you could find these via
http://bbs.onyx-international.com.cn
Also I would recommend
Tachiyomi app for manga if you did not have it already. Its awesome as you can download extensions inside the app to read and download manga from different sources.