Needing help with batteries on old 36volt cart

Bought an EZGO electric cart. This thing is old and looks to be a dinosaur. has a 36volt battery setup. Ran around in the thing for a few days no problems. then after I had charged it within a minute of driving it loses all power. So I am thinking batteries.

I put the batteries on the charger for 12 hours. then I unhooked all the batteries so they were separated. left them like that for another 12 hours. checked batteries voltage. had 1 battery read 5.8 volts. rest were 6.1 or better after sitting for 12 hours. hooked them all up and ran cart again. made it for a minute and started dying. pulled seat up and felt all the batteries. the first one on the negative side of of series was hot as heck. and it was the one that read 5.8. assumed it was a dead battery. replaced it with a napa 8146. hooked everything up and went good for about 2 minutes and started dying. pulled seat and of course another battery on down the series line is getting hot and now reads below 6 volts.

question is am i gonna be doing this til they are all replaced or am i gonna get lucky?
can just one bad battery cause it to die like that or do i have a bigger problem?
any help is appreciated thanks. nathan