Frankly, this.

honestly, it sounds like if you ruined 4 gameboys just trying to put backlights and prosounds in, you probably won't be able to cobble together a working one out of those 4. get someone else to do it.

What about the one with the broken cable? If you know where it's broken, couldn't you cut the end off and solder and tape the cable from the horizontal line PCB?

"I only go something out of it after moving the front pcb around while it was on"
One of mine started doing this the other day, it was kinda glitch like until it rested in a position it liked. All I can recommend for that is do what I did and try to bend the ribbon cable crease back into shape.

Coincidentally that same gameboy started the screen issues while I disassembled it to try and fix the right channel as well. Although I wouldn't say there was no right channel it was barely even noticeable though, like 5% of the lefts volume. I really have no idea how the right channel just disappeared like that.

I did come up with a work around though to get the right channel back. It turns out that the right channel was failing after the pre-pot. As much as I like pre-pot, I really wanted that and to be able to adjust the volume too. So in addition to my 1/4" pre-pot prosound which was wired to the points in this red box:
I soldered another set of wires to the same points then relayed those wires to an after market volume adjuster then wired the post-pot of that to the original headphone jack. Viola left and right channels fully functional with volume adjuster.
So there are two volume wheels one for speaker and one for the headphone jack.

@ GoingHam:
Well there is nothing visually wrong with them. It has all the looks of a broken wire (from my experience with cheap headphones), only working sometimes when holding it. And all buttons still work on all of them.

@2PLAYER:
I've already tried that, but didn't work. Also it isn't loose.

@soultron
Even the almighty fix couldn't seem to fix it...

Duct Tape.

If you need it for tomorrow it sounds like your only shot would be with the front pcb you describe as having no right channel? Is this audio? If so swap out the back pcb with another one. This may also fix the "looseness" issue you have. Just clean the contacts on the ribbon cable first. Pretty sure the rest of your front pcbs are scrap now.

Edit: also pics of the other front pcbs would help to determine if they're beyond repair.

I feel your pain bro. I ended wrecking like 4 1/2 DMGs in one way or another.
Its good to see you have 4 bottom PCBs still intact. Although just to be sure, I would do a test of all of the button's functionality.
From what you have described, the massive line & the torn ribbon cable PCBs are pretty much beyond repair. (horizontal technically could be fixed not easily though)

I'm not entirely sure whats going on with the other two. Could you please go into more detail of what is malfunctioning? Also pictures of any hardware or areas that might possibly leave some room for error.

Worst case scenario, you'll most likely purchase DMG for the collection. (Which is always fun)

Although you could contact ApeShit as he helped me out of a jam very similar to yours.
Four of my Front PCBs were cached while 1 remained somewhat functional. ApeShit was nice enough to preinstall two backlights of any color I wanted, I received the two boards in the mail. I have to say that his work is very top notch.

All of them have problems with the front PCB (and 1 failing back pcb, but thats real no problem). So after 4 failures backlighting, biverting and (rca)pro-sounding a dmg Iwanted to know if I could make a working one with the parts I have.

what I have:
-1 front PCB with a massive line on the screen (horizontally), likely happened while I was removing the foil for the backlight (I overshot with a Stanley knife, because I couldn't get it off).
-2 front PCB's with a (what seems to be (I only go something out of it after moving the front pcb around while it was on)) a worn out ribbon cable. ( one without a right channel and the other without visuals) (both seem to be from putting them to much in and out of the slot)
-1 with a torn screen cable (A bit to rough while cleaning the glue off behind the screen)

So can I make a working DMG with this (preferably really easy and short term, because of vacation tomorrow)?