How do you fix a stuck down volume button on car stereo?

first off is it the original stereo that came factory if it is try this solution:
1:turn ignition on but do not start
2: turn on stereo
3: do not touch anything else
4: wait 5-10 with stereo on and ignition on 10 min to be sure
5: after 10 min turn of ignition only remove key exit vehicle
6: set alarm
7: wait 10 more min
8 disarm alarm
9:put key back in ignition and set to on do not run
10: stereo should now work

your volume knob might be broken, volume button on the steering wheel can be stuck in pressed position.

check to see that the fader swich is not on

fine tuner spray in the switch

You cut into the worng wire i am sure, here are the wire functins for this car year, please redo the wiring and check all fuses under the dash and under the hood.
I assume this is a Sable?
2002 Mercury Sable Car Stereo Wiring Diagram
Car Radio Battery Constant 12v+ Wire: Green/Yellow
Car Radio Accessory Switched 12v+ Wire: Yellow/Black
Car Radio Ground Wire: Black/Light Green
Car Radio Illumination Wire: Light Blue/Red
Car Stereo Dimmer Wire: N/A
Car Stereo Antenna Trigger Wire: N/A
Car Stereo Amp Trigger Wire: N/A
Car Stereo Amplifier Location: N/A
Car Audio Front Speakers Size: N/A
Car Audio Front Speakers Location: N/A
Left Front Speaker Positive Wire (+): Orange/Light Green
Left Front Speaker Negative Wire (-): Light Blue/White
Right Front Speaker Positive Wire (+): White/Light Green
Right Front Speaker Negative Wire (-): Dark Green/Orange
Car Audio Rear Speakers Size: N/A
Car Audio Rear Speakers Location: N/A
Left Rear Speaker Positive Wire (+): Gray/Light Blue
Left Rear Speaker Negative Wire (-): Tan/Yellow
Right Rear Speaker Positive Wire (+): Orange/Red
Right Rear Speaker Negative Wire (-): Brown/Pink

Hi, your factory Sunfire wire colors are pasted below. The yellow wire should be accessory. This should connect to the stereo's red power wire. The orange "always hot" wire should connect to the stereo yellow wire--this is only used to keep your station presets in memory. Please let me know if you have more questions, and thanks for using FixYa.

2004 Pontiac Sunfire Car Stereo Wiring Diagram
Car Radio Battery Constant 12v+ Wire: Orange
Car Radio Accessory Switched 12v+ Wire: Yellow
Car Radio Ground Wire: Black
Car Radio Illumination Wire: Gray
Car Stereo Dimmer Wire: Brown
Car Stereo Antenna Trigger Wire: Pink
Car Stereo Amp Trigger Wire: Pink
Car Stereo Amplifier Location: N/A
Car Audio Front Speakers Size: N/A
Car Audio Front Speakers Location: N/A
Left Front Speaker Positive Wire (+): Tan
Left Front Speaker Negative Wire (-): Gray
Right Front Speaker Positive Wire (+): Light Green
Right Front Speaker Negative Wire (-): Dark Green
Car Audio Rear Speakers Size: N/A
Car Audio Rear Speakers Location: N/A
Left Rear Speaker Positive Wire (+): Brown
Left Rear Speaker Negative Wire (-): Yellow
Right Rear Speaker Positive Wire (+): Dark Blue
Right Rear Speaker Negative Wire (-): Light Blue

1983 Chevrolet Chevette Car Radio Wire Guide
Car Radio Battery Constant 12v+ Wire: Orange
Car Radio Accessory Switched 12v+ Wire: Yellow
Car Radio Ground Wire: Black
Car Radio Illumination Wire: Gray
Car Stereo Dimmer Wire: Brown
Car Stereo Antenna Trigger Wire: N/A
Car Stereo Amp Trigger Wire: N/A
Car Stereo Amplifier Location: N/A
Car Audio Front Speakers Size: N/A
Car Audio Front Speakers Location: N/A
Left Front Speaker Positive Wire (+): Tan
Left Front Speaker Negative Wire (-): Gray
Right Front Speaker Positive Wire (+): Light Green
Right Front Speaker Negative Wire (-): Dark Green
Car Audio Rear Speakers Size: N/A
Car Audio Rear Speakers Location: N/A
Left Rear Speaker Positive Wire (+): Brown
Left Rear Speaker Negative Wire (-): Yellow
Right Rear Speaker Positive Wire (+): Dark Blue
Right Rear Speaker Negative Wire (-): Light Blue
This will get you fixed up. Enjoy the tunes!!

Sometimes you can press and hold down the CD's forward and backward track buttons or play and eject buttons to release the CD. Contact your Chevy dealer and ask a Service Consultant if the Delco unit has this feature.

Car Radio Battery Constant 12v+ Wire: Blue/Yellow
Car Radio Accessory Switched 12v+ Wire: Gray
Car Radio Ground Wire: Brown
Car Radio Illumination Wire: Green
Car Stereo Dimmer Wire: N/A
Car Stereo Antenna Trigger Wire: Black/Red
Car Stereo Amp Trigger Wire: N/A
Car Stereo Amplifier Location: N/A
Car Audio Front Speakers Size: 4′
Car Audio Front Speakers Location: Doors
Left Front Speaker Positive Wire (+): Pink
Left Front Speaker Negative Wire (-): Purple
Right Front Speaker Positive Wire (+): Green
Right Front Speaker Negative Wire (-): Blue
Car Audio Rear Speakers Size: 4′
Car Audio Rear Speakers Location: Side Shelves
Left Rear Speaker Positive Wire (+): Black
Left Rear Speaker Negative Wire (-): Yellow
Right Rear Speaker Positive Wire (+): Red
Right Rear Speaker Negative Wire (-): White

pls rate

Your problem is a common one with AUDI sound systems
Microcontroler in you device is failing.
When the stereo warms up, it stabilizes.
I know people who resolved thair situation by installing u 5W bulb inside the stereo to heat up the microcontroler. The solution lasts for a very short time because microcontroler burns up.
Second solution is to exchange the damaged microcontroler but you must find a person who knows what he is doing
And for the end, I never succeded to repair mine :)