any thoughts abs light and speedo
 

I was driving up to a store and had been driving the truck fine before for about 10 minutes anyway parked at the store and the wife decided she wanted to stay in the truck. so i went to crank truck back up and clicks and nada. Guy i bought the truck from told me he caught hell with battery cables getting a good connection so i fought with those for a while and then decided I would try a jump. Jumped off but when driving it home the abs light was coming on randomly , speedo at around 10-15 mph at a dead stop but otherwise working and when i hit the brakes atleast twice the radio shut off. Got home had the same prob cranking so i figured i would try another battery. that one didn't fit so i put the original one back in to roll up the windows figured I would mess with it in the morning.

Now the durn thing works fine. Any ideas for stopping this from happening again?