That's the ribbon cable for your trackpad. Not likely any connection to a temp sensor fault.
I think you will need to remove the trackpad to fully seat that connector.
(Hopefully, you have not re-glued the replacement battery yet!)
Follow the steps to remove, re-seat that cable, then reinstall the tracpad.
If your trackpad is broken or needs to be removed for easier access to the battery, follow these steps. For your safety, discharge your MacBook...
www.ifixit.com
(Be careful, don't lose any of the tiny round washers, they are important for proper mechanical seating so the trackpad is positioned correctly.)
Step 21 and 22 will show you more about that connector area.