I have a iphone here that's from week 30, and can only get it in dfu mode. the phone won't boot, no apple logo, no triangle, nothing.
When in dfu mode it starts the restore, but after a while itunes gives me a 1601 error.
Does anybody know what this can be?
I also tried to swap the commboard with a week 51 iphone, but then both of them have the same problem

This smells like the logic board problem. See: http://www.hackint0sh.org/forum/showthread.php?p=204179

If the phone heats up after being plugged in to charge for a while then that'd definitely the cause of your problem.