
Do you see why? The gamebit screw has been replaced with a Phillips one and there are scratch marks around the screw :/ Somebody already tried to repair this. Dude, take hint! If you're too dumb to open the case don't try to repair it!!
Inside, I think I found the worst recap attempt I have ever seen in my life:

There were caps falling of the board as I took it out, just WTF are you doing... THANKFULLY the idiot realized that he can't solder and stopped at the sound board.
Power board looked & measured fine. Logic board had a lot of clearly leaked caps but was undamaged otherwise:

The console powered on, but just gibberish on the screen. I decided to do a full recap, beginning with removing the old caps on the logic board and clean everything. Took a lot of scraping with flux & solder and lots of wiping with IPA:

Look at C1 at the bottom left of the cart slot, there was a lot of corrosion I had to scratch & re-tin a lot of traces. Other pads were fine and could be reused without issues.
With new caps:

I did not want to spend any money on this, so I used the parts I had. I didn't have higher capacity ceramic caps so I used electrolytics. I only have kits of random chinesium caps stocked, so I used those. Didn't have a 68uF cap, used 100uF. I tested all caps with an ESR meter before using them, one actually had bad ESR, the other ones were way lower than anything Sega used originally, I'm sure.
After this, GG powered on and had LED & backlight. Tried a game, ran & worked first try. Nice!
So, next up is the sound board. I removed the traces of the terrible repair attempt and tried to remove all the corrosion:

Yikes! Lots of missing traces and pads. The melted connectors etc. wasn't me. Sigh.
I ran some bodge wires etc. and installed new caps:

Gave the repaired sound board a try and... nothing. Damn. Thankfully tried the headphone jack and that worked perfectly fine. Great, at least there's nothing fundamentally broken. I tried a different speaker, no luck. I thought maybe the mechanism for switchover was broken and debugged a bit. Turns out it was simply a corroded via that caused the ground connection from the speaker to float. Ran another bodge wire:

So everything works now, I tried to put my GG back together:

Womp Womp. The caps I used on the sound board were too tall. Should've just used SMD electrolytics, got those on hand, but they're annoying to solder if you can't use hot air and especially if the pads are missing...
I just put in some new caps, this time lying flat:

The positive trace for C7 was starting to lift at this point so I ran another bodge wire.
But finally, success!

I did not try to replace the scratched lens, clean the buttons / membranes / contact points or remove dust from the screen. I'll open up and deal with the front housing when I have quality replacement lens on hand. What I got now is really crappy.
For one day of work and the price of a few Chinesium caps I'm quite happy with the results. Let's see how it lasts
