Upgraded RAM now computer dead, no power, no fan, no lcd, nothing

OWC does not say to leave the machine plugged in to a grounded socket. The instructions they provide are extermely straight forward. Re-watch them and you will see they clearly indicated to unplug the machine. OWC's instructions can be found at:

http://eshop.macsales.com/installvideos/imac_mid_2011_mem/

I would recommend calling OWC for support and if they cannot assist then you need to take it to your local Apple Store or AASP to be looked at.

I followed OWC's awful advice to leave the computer plugged in to a grounded socket (to discharge static, supposedly).

Sorry, but I just watched the instructions for your model and it very specifically said to shut down and unplug the computer. I'd contact their support and ask for assistance or take it to your nearest Genius Bar.

They said the only risk was a possible shock not that the computer itself would be damaged.

I'm sorry about your, well, mishap. I would never interpret that as meaning you can change out electrical components while it is plugged in with current flowing in.

OWC's instructions are beside the point.

Well, we have a difference of opinion here; I believe they do matter because they are correct.

According to their instructions here:

http://eshop.macsales.com/installvideos/imac_mid_2011_mem_l/

exactly at the 1:14 mark, he says "after shutting down and unplugging...."

If you have homeowner's insurance, you may want to inquire if such damage is covered. Good luck.

Before doing anything else, make sure the RAM slots are clean and that the modules are fully seated. When I upgraded the RAM in my 2010 iMac 27" (with OWC RAM) I noticed it took quite a push to get full seating.