Wont start after GPR relay drained batteries

[utahboy]

I have an 02 7.3L. I replaced the glow plug relay only to find it was the wrong relay. The relay stayed on the whole time it was installed and drained the batteries. While I was trying to start the truck and troubleshooting why it wouldn't start it drained the batteries. I took the wrong relay out and put the old one back in (it started before as long as it was plugged in and warm). After installing the old relay it wont start. Its nice and warm and the batteries are 100% charged. It cranks and cranks and cranks. No smoke. I've checked every fuse and relay...about three times each. Can't find a bad fuse. I get a code of P0380- glow plug circuit. I'm lost and ready to put a rag in the tank and light it on fire.