Thanks for the reply!
Well, the nasty question is which 3 of the 6 boards are failing, yours or the assemblers
Actually, of the revision B boards, 2 out of 3 made by the assembler failed. Two of the three I made in my toaster oven worked. I made two of an earlier revision and both worked. I think, that was months ago now. I checked the work of the assembler and the chips and other parts all seem to be in the correct spots, with the correct orientation. I can't see any shorts even with my magnifier (not that its a great magnifier) and none of the chips get particularly hot.
Ironically, the last board I made failed in this same way, which is what motivated me to hire the boards out.
Can you check the crystal to see if its oscillating? Maybe you have the wrong load caps on this time around?
Caps all look the same so they could be wrong. If the caps were wrong, would it have worked for a little while?
Crossroads suggested I use an o scope with a low capacitance probe to see if it is oscillating. I don't have one, so I am going to ask around.
Are the voltage levels right? Can you probe them with an oscilloscope to check for signal quality? (though I'd spend more time on the oscillator question)
The Vcc of the MPU has 4.98 V according to my volt meter, but of course its too slow to see if that voltage dips if the chip fires up. Again, i need an O scope I guess.
Are there any tantalum caps in your design (and if so, are they backwards)?
No there are none.