Incorrect batteries

[Kewi]

Literally a good friend of mine owns a 2005 Yamaha 48 volt very nice custom cart. He had an issue with a couple batteries so decided to buy all new ones. Here is where the problem comes in. He was not totally understanding the battery voltage and our local Farm and Fleet did not catch it. He took in six 8 volts but came home and installed six 12 volts. Now it’s dead, no movement, no power. I’m going to look at it and assuming a breaker tripped but could use a heads up on possible issues. I have two Club cars so not familiar with Yamaha but must be similar. What do you think?