weird situation before test drive

Got in the 2015 that I was going to test drive. Hit the power button only for it to do some weird stuff on the dash complete with "error, take to dealer" message. Then it proceded for nothing electric to work at all. Totally dead, even door locks. The salesman assured me that there was a charge on it. Could this have been the 12v being dead? If so, I assume it would still be safe to buy should I be able to strike the right deal?

If you can't drive, then don't buy it.

It may just be a 12v battery issue, but it could be a bigger problem. Use it as a bargaining chip. Make sure it is fully repaired and operational before signing the paperwork. See if you can get an extended test drive to make sure there are no other issues that pop up.