there is a little pad that sits right under this for some pressure, but it looks like its under there. if not, egr found your problem probably!
try cleaning the contact pads for the EL panel too. if the button contacts in this unit were so dirty they didn't work right, most likely some of that gunk got into this area too. clean both the EL contacts and the ones on the PCB, because if you leave one dirty and clean only one you'll just transfer dirt to your clean surface. like how when people put new edge connectors in a NES then ruin them by inserting terribly dirty and gunked up NES carts.
if the leads in the EL panel just came loose from the membrane which illuminates, you'll probably get some flickering instead of it staying off (and you can generally 'fix' this with some pressure to encourage them to sit on the membrane again). if its just an outright dead panel, i'd say its a contact issue or else the leads in the EL panel were severed somehow. which shouldn't happen unless you were pretty rough with it, its a good quality part.
well anything could be the problem i guess. like cleaning liquids into the EL circuitry which shorted something out, etc... its probably with the EL panel though, they can be a little finicky sometimes.
when you turn the switch to have the light come on, does the console have any high pitched electric whine sound added? you can hear the EL circuitry in a light from the outside if you know what to listen for.
