My truck has been sitting for a while, like a couple months. Last time I started it, it needed a jump. I bought a new battery and hooked it up correctly. But now it won't start even with a jump. There's no click of the starter, the dome light doesn't come on, the radio is dead, there seems to be no electricity getting to the vehicle at all. I'm not sure what my next step should be or what the problem could be. Any ideas? I'm hoping it's nothing too expensive, but fear the worst.
First check for blown fuses. Often they blow from the surge of connecting the battery or jumper cables. If they're okay, use a test light or digital voltmeter to measure the battery voltage right on the posts. Next, one at a time, move the probes from the battery post to the cable clamp. Move one probe from the positive cable clamp to where the smaller wire bolts to the under-hood fuse box. Move the negative probe from the cable clamp to the body. You're looking for the first place you do not have voltage. That will be the connection that is loose or dirty.
You don't have to replace the battery when it runs dead. Just charge it at a slow rate for an hour. All vehicles with computers have memory circuits that draw a small current from the battery all the time. Unless the manufacturer specifies otherwise, the industry standard allows a draw of up to 35 milliamps, (.035 amps). At that rate a good battery will still start the engine after sitting for three weeks. It may not start after sitting longer than that.