fussion hybrid 2011 have a bad sensor EV/ICE mode

[HVbat]

I contacted a person that sell their fusion 2011 hybrid for $800, 151 miles and work but indicate that will require a electronic repair with a sensor that change Electronic battery to ICE.
But the person doesn’t have more information
I would like to know what the problem is or not worth the purchase, I am currently without own transportation.
Thanks in advance.