Camry :: 2004 - Dash Stopped Displaying Information - Fuel Gauge / Speed

Last week, our 2004 Camry's dash stopped displaying information - fuel gauge / speed / etc. two nights ago, I reseated a number of fuses, and it worked for a while, but stopped working again yesterday. All the fuses looked intact, even though some of the contacts were a little gunky. I cleaned them off, but it continues not to work.

Additionally, after reseating a number of fuses, I get 5 quick beeps when turning off the car, which may be coming from our aftermarket radio.

I read on another site last night to disconnect the battery, and that may reset the computer, and relight the dash. I did that, it didn't fix the problem, and afterwards when I started the car the idle was so slow the car wouldn't even stay running. After about 20 minutes, the idle was still very low, but the car would run. When I checked it this morning, it was idling fine, but the dash still wasn't lighting up.

The seatbelt lights and gear light up ok, but nothing else on the dash works. Battery, alternator, dash? What does this sound like?