[sdiy] P600 - no workee

[Hermitage Heart]

Greetings all,  harken unto my tale of woe.

So I decided to clean the key contacts on my P600 and while I had it  
opened, to upgrade the eprom w an ROM image found online.
Cleaning the keys pretty much is a no-brainer. I've done this many  
times over the years with various poly-sixes, etc.
I'm newish to the prom burning thing, but here's what I did:

I backed up the old eprom (6.0.5)
blanked the chip (UV erased)
verified the ERASE
burned the new ROM (6.0.8)
verified the BURN
installed the chip
installed keybed, reassembled. power on:

no LEDs, no sound, no magic smoke.

I've checked power to the boards  +15/-15/+5 where you would expect them
I've wiggled /reseated connectors all with no luck.
checked for bent pins on the eprom, & double checked that the chip was  
correctly oriented.

I even re-blanked and re-burned the old ROM version - still nothing.
I would kinda expect that even with a bad ROM (or maybe even without  
an OS chip) that there would still be and LED or two lit.

suggestions on how to proceed from here?

thanks in advance for your advice.

HH