Precision m4700 - No POST

Precision m4700.  Normally on most of time.  The other day had to power off and when went to power it back on, nothing.  System has all 4 banks populated with 8g for 32g total.

Power light comes on, HD light flashes, Optical bay light flashes, sound (mute, -, +) all light up, power light stays on solid.  No LED codes from HD/Batt/Wifi.

Have removed ODD, HD, mSata module, wifi, all ram, no changes.

Tried with/without battery, tried different ac adapter.  Tried with HDMI cabled up, tried with VGA cabled up.

One time, when I removed a memory module I got the 'memory has changed' warning, thought I'd found it, turned it off (stupid me) and then never got it again.  Even changing other memory didnt result in another warning.

No beep codes.

Tried different memory and memory configurations.  Nothing.  Using incorrect memory (PC3-8500 for example) resulted in LED pattern indicating a problem with memory configuration)

I've disconnected CMOS battery overnight and bled any residual power, nothing.

If I remove all memory and power on, the LED codes DO indicate no modules are installed.

If I press and hold FN while turning on power, I get a blinking battery light, but can find nothing LED wise that matches OFF, BLINKING, OFF

If I press D and power on the display comes up and cycles between White/Red/Green/Blue/Black for 30s or so.

Of course, warranty ended the end of June.

Any thoughts?