no power at all
 

Just drove my car to work and came out to leave it wouldn't start there is no power at all no headlights, interior lights and no crank at all. Has a new battery connections are tight, full tank of gas starter is new. What could be the problem?

Alternator perhaps, did you left your headlights on? Jump start the car, measure the voltage, should be around 14.5v, or your alternator is bad.

There is a main fuse attached to the positive battery connection. It is 140 amps. If this has blown, it's almost the same as disconnecting the battery cable. If this fuse is blown, there is a serious problem somewhere.

A bad alternator won't prevent a car from starting, it will prevent it from running.

As stated, maybe you left something on and it drained your new battery?

Check fuses, wiggle your battery connections, check grounds

A bad alternator can have a shorted diode that drains the battery while not running. Also a bad alternator will not charge the battery, allowing it to drive that last time and then be parked, unable to start again.

Have someone attach jumper cables to your battery.
Don't start it yet. Do the headlights work? The wipers? Other things?

Next, start your car.

If you are able to run the accessories, you have a good main fuse.
If the car starts, great.

Then your problem would be a discharged battery.

Yes, I have seen a bad diode in the alternator cause this.

Thank you Captain Obvious:D