After searching in forums and online, it seems relatively simple to simplify the ROM, that is, after decompressing the original ROM, delete useless things and package the signature. I simplified it with the ROM of sense2. 1+andriod2.3 (only a few ringtones and facebook were deleted), and then packaged the signature (the signature tool was downloaded from the Internet), indicating that the signature was successful. I generated a signature compressed package and uploaded it to the sd card. After the installation was resumed, all of them were erased indiscriminately. I found that the ROM packages on the sd card were all deleted.