I have an idea but i am not sure if the same pins work for your laptop
Edit: They are almost the same.
sudo apt-get install alsa-tools-gui
sudo hdajackretask
Select the sound card on top
On the right side select show unconnected pins
Find the 0x14 pin, check the override button, and set it with the option "Internal speaker"
Find the 0x17 pin, check the override button, and set it with the option "Internal speaker (Back)"
Then click the button Install boot override
Reboot to see changes.