99 Blazer won't crank

i'm about to kill myself. this friggin car has been such a headache. here's the latest problem.

my son had it at school. wouldn't start. got it jumped, drove it home and let it run in the driveway for a bit. shut it off, went out the next morning and it cranked slightly, but wouldn't turn over. put the batt on the trickle charger, wouldn't take a charge. just put in a new batt. now all the lights are on strong, everything works, but when you turn the key to 'start' it goes dead. completely dead. as in nothing. you can hear the fuel pump working when you turn it to 'run,' radio works, lights, everything comes on, but when you put the key over to 'start' it just completely craps out.

i've searched the threads, but can't find anything like this.

is there a maxi fuse? could that be it? some other electrical component that's out? i made sure the battery cables are tight. could i have burnt out the starter trying to crank it? (it was wicked cold that night and it didn't sound too happy).

Could be the ignition switch is bad and drawing from the battery even when the vehicle is off.

got it. turned out to be the cable between the solenoid and the starter itself. completely corroded through.