mmm ... I'm surprised the Apple Genius told you is was the fan. To be sure I would recommend running this App (full version): TG Pro. Post a screenshot of what it shows you so we can be sure.
Given your symptoms, my guess is your battery is swelled up causing pressure on the backside of the trackpad & keyboard. I would recommend you run this App: CoconutBattery. Again, post a screenshot of the main screen so we can see what it tells us.
TG Pro can also help us isolate the problem down to the battery as it will report a higher than normal temp while charging.
OK, let your system run a bit longer on battery so the battery is lower. Then, plug in the MagSafe adapter so you can charge the battery up.
Take another snapshot of coconutBattery at this point so we can see how low the battery is and the temp as it starts to charge VERY IMPORTANT: Leave the coconutBattery window open so you can see it (don't cover it up)
As your system is charging type on your keyboard and use your trackpad as soon as it stops working take note of the batteries temp. Unplug the charger and let the system cool as best as you can see if the system is able to recover in 1/2hr increments. When it does take another snapshot of CoconutBattery and tell us the temp you noted when your keyboard & Trackpad stopped working.
If you have an external keyboard you could plug it in or Bluetooth, so you can capture the point your builtin keyboard stopped working.