P38 Engine won't start after being powerwashed-Need Help

My neighbor powerwashed my 98 4.6 HSE engine. it was running fine while he did it, and even the following day. However, this morning when I came out to start, it would crank but not start. I'm guessing he got water somewhere he shouldn't, but what do I do??

Any help is greatly appreciated.

First step is to take out all the relays and fuses under the panel in the hood one by one, blow out/dry off the bottoms, and replace.  In my blazer I got some water in there washing out the engine bay and it caused the same problem...water got under the fuse panel, and over the rest of the day worked under a contact somewhere....a few of my relays had water under them, after a quick dry, all worked!

I checked fusebox and I have nothing that is wet under there. Any other suggestions?

If I remember right, and I may be wrong, isn't your ECU mounted in the engine compartment? If so that will be your problem, and it will need to dry out before it will restart.