What are the causes of phone crash, spam, slow response, etc? And how to deal with it?

LZ hard grid machine is recommended. Methods Turn off the phone first, and press and hold the call key, power key, asterisk and 3 at the same time until the phone is completely turned on, but remember to back up the card holder before hard grid machine. Open the card holder directly, press the option, and you will see the key. In this way, LZ can reinstall the software and restore all factory settings. In addition, if LZ wants to save the original SMS, it needs to use QQ synchronization assistant to transfer the SMS to QQ in the lattice machine, and then reinstall QQ synchronization assistant when the lattice machine is ready, so as to get the SMS back. If you have any questions, please ask me.