Solved! Dell D610--No post, no fan, shuts down after boot

A while ago my D610 laptop had a number of shutdowns (perhaps heat related) and finally stopped booting afterwards. First, it was posting and loading BIOS, but eventually nothing: computer turned on but no post.

A few months later I finally decided to replace the motherboard and upgrade the RAM at the same time (2x1GB DDR SDRAM 533Hz Certified Dell RAM). Result: no post, no beeps, no fan. Only HD spin. The machine shut down automatically after about 6 seconds. I/O light comes on, stays on until eventual shutoff. Processing light comes on, doesn't flicker. Battery light comes on, stays on when battery installed.

Tried with just running CPU and motherboard. Same result (except, obviously, no HD spin).

I purchased a new processor (Intel M770 2.13Ghz 533Mhz FSB) and a new fan, and recently installed those (used master cooler thermal grease). STILL the same result... Power supply is fine--it checks out with multimeter.

I tried resetting CMOS. Same result.

What else could I even try?

EDIT: Update. Apparently the POST test uses the flashing LED lights (scroll lock, caps, etc.)

With memory removed, I get Num lock flash, Caps lock on, Scroll lock on.
With old memory, I get Num lock off, caps lock flash x10, scroll lock off
With new memory, I get Num lock off, caps lock flash x10, scroll lock off

So, perhaps either old memory and new memory are both OK or both faulty. Unfortunately, I can't find the codes are for the D610...
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Dell Latitude D610

Currently Installed:
Intel M770 2.13Ghz 533Mhz FSB
2x1GB DDR SDRAM 533Hz Certified Dell RAM.
OEM Genuine Dell Latitude D610 Motherboard ATI Mobility Radeon X300 64MB

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