Replaced alternator, now car won't start

ok so your acid level in the battery needs to be checked if its at the right level get another battery because there are dead cells in it. if the alternators good check it to be sure even new parts can be bad. ok same problems with a good alternator bad battery. Hope this helps

have the charge circuit checked by an accredited auto electrician as you may hve damaged the alternator or voltage regulator which may be in the ECM unit

Unusual the dealer can't or won't find the problem.
A mechanic would check everything in that circuit for shorts to ground.
Was the fuse blowing before the alternator and battery were replaced ?
Based on the wiring diagrams I would vote for a defective alternator.
The 10 amp fuse number 8 powers the cluster which also goes to the alternator. If the alternator shorts out internally it would blow that number 8 fuse and take the cluster with it.
The other circuits you mentioned are controlled by the key switch but are fused after the switch. So if the switch was causing the problem it should be blowing a 40amp fuse.
I would probably take the alternator off and have someone else test it.

Do you know how to use a DVOM - digital volt ohm meter to trouble shoot automotive electrical circuits ? Using a wiring diagram to find testing points in the B+ power flow of the vehicle electrical circuits .
Free wiring diagrams here http://www.bbbind.com/free_tsb.html Enter vehicle info. year , make , model , engine size . Under system click electrical distribution , then under subsystem click power distribution . Click on the search button , then each link one at a time !
. stop lamp & park/horn circuits grounded on load side. What can cause this? A direct short to ground .
Finding The Source Of Electrical Shorts In Your Car

Electric Testing Techniques You Need to Know

First thing is to perform an amp draw test,not to difficult.Buy a cheap volt/ohm/amp meter and set for dc amps,then disconnect car battery neg cable and attach one lead to neg bat post and the other to neg bat cable.At this point your are measuring current flow out of battery into electrical system.Now pull fuses one at a time while observing current flow,when one of these fuses are pulled you should see a lot less current being drawn,headlamp,cig lighter,heater fan circuit ect.Once the high draw circuit is isolated you can focus your attention on that.A through inspection must now be made to the wiring,components and fixtures of that circuit,much more difficult.If this car has ever been wrecked i would pay close attention to that area.

it probley shorted out the brain box

REPLACE POSITIVE BATTERY CABLE.CHECK ALTERNATOR FUSE AND CHECK ALTERNATOR VOLTAGE REGULATOR WIRES FOR DAMAGE.HOOK VOLT METER TO BATTERY FEED WIRE MAKE SURE 12 VOLTS GETTING TO ALTERNATOR FEED WIRE TO ALTERNATOR POSITIVE HOOK UP IF NOT YOU HAVE BLOWED FUSE TO WIRE FEEDING ALTERNATOR COULD HAVE FAULTY BATTERY POSITIVE CABLE OR CABLES CORRODED NEED CLEANING.

The short is probably in the alternator. Remove the alternator and have it tested at the parts store or test it yourself. Blown diode will allow a direct discharge of the battery.

you alternator is no good to ceck alternator start car while running take off positive cable if it dies your alternator is no good but thats what it sounds like

RAP stands for Retained Accessory Power. It is the circuit responsible for powering accessories when the key is off. Sounds like something is staying on that shouldn't. Hard to say what though with the information here. if this started happening right after you put in the new radio i would check into that. otherwise start checking accessories like power mirrors,seats, locks and see it something is staying on that shouldnt. i good one to check would be the glove box light or the light under the hood. you can unplug them and then test your draw to see if thats where is was.