alpine cdm-7854

ya i bought this head unit for 5$, im planning on fixing it and putting it my moms van. i work at best buy, and when i asked her if she wanted me to put in a stereo for her she said "yeah,  but can i get an alpine" and best buy doesnt carry alpines till feb. so my employee discount was out of the question. i talked to a person that was buying a new head unit, and had this one, they said a few of teh buttons dont do the correct functions (both volume buttons turn down the volume, mute button turns it up, and you knda gotta press a combination of buttons to do anything else other than switch tracks or change stations) the sound quality is still great on it, she doesnt need a ton of power or anything, she just trusts the alpine name, and i dont blame her. but what would u suggest i do? should i try opening the back of the face and soldering some stuff? or just try and find a new face, or the same one w/a broken amp or something?

if any of you know where i could find the wiring diagrams for the face let me know, it would be nice if i could just fix it myself and not have to buy anything, thanks.