Water killed my Blazer?
 

I had a leak with my power steering pump so I swapped it yesterday, just to discover the it was the high pressure line and not the pump its self. After I got it all put back together I and started to clean the front drivers side of the engine bay due to all the PS fluid sprayed out over time. I wiped it dont with rags, cleaned underneathand then sprayed a little water into the lower part or the engine bay. Evidently I got something wet that doesnt like water that much. When I went to crank her back up for the furst time since I put the new high pressure line in and cleaned, the starter(or selonoid) clicked once and everything went dead. I disconnected the battery and put the key to ACC and the radio comes on and dash lights up as usual. But when i try to crank it the starter(or selonoid) clicks then all goes dead, no more lights in dash, radio, nothing. At this point I will disconnect then reconect the battery and it is a repeat. I have had a fan blowing down into the engine bay all day long and it still isnt cranking. I have checked my fuses and they are fine and the starter has NEVER had a problem, so im assuming the water made a short in some electrical component. Did i kill my ECU? What should I do? What can it be?

Sounds like you may have damaged the negative cable when working on the pump... or it could just be a coincidence.
Check both battery cables for bad connections and for corrosion... cut into the insulation and look for greenish or whitish corrosion at the ends. When you have eliminated the cables as the problem... the battery is next on the list. Check the water level in it and put a battery charger on it. Once it is completely charged, take it into an auto parts store and have it load tested. (they will also charge it for you if you don't have a charger)
If the battery is more than 3 to 5 years old, I would be suspect of it.

But why does everything go blank until i disconnect both cables and then reconnect? It doesnt act like the battery is dead. If i just put it to accesories everything works fine, but when i try to crank it kills everything, and i have to disconnect and reconnect to get my accesories working again. its like when i crank it, it kills power to everything and to try again i have to do the battery thing. when i sprayed the water it was a very small amount, but i know there is a few wires down there. i think i created a short, im hoping that when the water dries up the problem is gone, but im scared i fried something.

That sounds exactly like a bad battery or cable to me. Try swapping in a temporary battery out of another vehicle and see what happens... I would also just go ahead and replace both cables if they are the originals. Battery cables have been made cheaper and cheaper in the last 15 years or so and I would only expect 5 to 7 years of service out of them depending on the environment they are used in.

Went out this morning to try to crank her up and I had no power at all. So I disconnected the battery and put it in my car and the car fired right up, so the battery is good. I the n pulled it out and put it back in the blazer and she fired right up. Weird. So I think that i just got water in something and once it dried up all was good. She ran a little rough for a few minutes but all is good now. Thanks for the help BandidoLenny. Much appreciated. Until next time, See ya!

Once again... check (replace) the cables...

first dont EVER spray water in an engine bay without covering ALL electrical components and carb etc..