The reason why you couldn't exit the novel on the full screen of the P2 might be due to the following reasons: 1. Software problem: You can try to re-install the reading software or update to the latest version. 2. Reading software conflict: Remove the recently installed reading software and then re-install a normal reading software. 3. Phone system failure: You can try to restart the phone or restore the factory settings. 4. Reading permission: Check if the phone has reading permission. If not, please grant reading software permission. 5. Device Overheating: If the phone is overheated during use, it may affect the normal operation of the software. You can try to close other applications to reduce the load on the phone. If the above methods cannot solve the problem, it is recommended to contact the customer service or professional mobile phone repair personnel.