If this battery issue came immediately after purchasing your device, be sure to notify the manufacturer of this issue. Otherwise, you will have to replace your device's battery by opening the laptop and locating the battery slot.
Before checking if your device's wifi port is damaged, be sure to unplug and restart your wireless router. Also, be sure that your wireless internet drivers are updated. If these are not the case, then it can be that your device's wifi port is faulty. Opening your device and replacing its wifi port may resolve your issue.
Since you can hear sound through headphones, we can safely eliminate any audio software issues. Some common issues for laptop speakers are blown out speakers, water damage, or loose wires. You can open your device to examine for any of these possible issues.