After I finished installing my 408 I noticed none of my buttons on my steering wheel work anymore. I have no idea what it could be, any ideas? Everything is stock as far as audio.

 

I dont know if yours went bad, but mine went out on one side so I had to replace them...They are not hard to take out, just unscrew the bolts (i believe there are two) on the back side of the steering wheel that hold the airbag in and remove the air bag to gain access to where the steering wheel controls plug in.
Other than that, I would just check all the connections running from the headunit to the controls

 

I think your 408 is bad you can give it to me...? Check the wires leading to the headunit make sure nothing is getting pinched.

 

Check the 1AMP Steering Wheel Control fuse in the fuse panel on the driver's side of the dash (name on panel is abbreviated).

 

There are two 1-amp fuses labeled STG WHL CNTRL in the dash fuse panel. Fuse #3 is for the steering wheel control button power and fuse #13 is for the steering wheel control button illumination.

 

both fuses are good

 

could be the little buttons behind the steering wheel buttons. They are a soft rubber and the plastic button depresses them. Occasionally they will blow out and a cheap fix is to get the little red coffee stirrers and cut them into little like 3mm cylinders. then you can insert them carefully into the rubber pieces. this will make transfer the "press" to the circuitry.

OR

it could be the circuit board crapped out and you need a new one like I did so long ago.

 

Dude, you're the man! I just fixed my steering wheel buttons; replaced the little rubber buttons with pieces of a squirt tube from a WD40 can