Everyone often says "you have a short". You know what the likelyhood really is that we all have short circuits when something is malfunctioning in our high powered car audio systems?? Not very!! Shorts are what FUSES are for!Good chabce you a have a bad cell or b a short.Yes you can take tge battery out and play the radio at a moderate volume and see how fast voltage falls. Just single out each battery and test tgem watching voltage drop.. If it drops off fast and struggles to recover its more tgan likely bad
John Kuthe..