Port LEDs constantly ON, no front led, Power Adapter okay. No function

During a thunderstorm The A1354 's power adapter blew. This is not a prob, I've got others delivering what's needed. But plugged in, AirPort Extreme still doesn't work.

Symptons: 1) big front led doesn't react in any way. 2) small leds of all three LAN-ports are constantly illuminated. 3) the airport doesn't show up, when searching for it via WLAN nor via airport-app [don't dare to connect via LAN-cable to PC]

What I did: 1) I completely disassembled device, searched for broken/cold parts/solder joints attentively - without results. 1.1) But on WLAN-card's board the two quadratic chips and the grey rubbers - on the card itself as well as on the counterparts of the inner metal housing - had an oily coating; but everything looks okay here, too. Cleaned them. 2) Measured power starting at the jack, following the first very few parts - seems to be ok. 3) Measured the leds which build the big front led - 4.8 volts are present at each of the three leds to ground. 4) Tried to reset the device (switch is okay), but no success at all. 5) Measured battery, it's voltage is okay.

That's it, I couldn't analyse or even repair any more.

(By the way; this AirPort Extreme has four antennas?!)

Any ideas, or is the airport's board damaged completely?

Thanks for your thoughts and help...