I purchased one of these for <$10 shipped, to run in an old NDSLite as it seemed some people had luck with them.
I was able to load DSOne EOS files onto an SDHC card, but when attempting to launch nds files it always hung with the "DSOne EOS loading..." splash on the bottom screen, and a black screen on the top.
After running the built in self test (hold L&R down while applying power). I saw:
Since I always had this problem (not degradation over time), this seemed like a hardware problem to me.
With nothing to lose, I applied some flux around the sram chip and turned on the hot air gun (~1min at 250C and maybe 30s at 350c):
View attachment 270383
Everything's working now!
If you do this, be careful not to move the PCB until it's cooled so you don't cause the components on the backside of the board to move/fall off (they're probably also reflowing).
I also modified the plastic case a bit as C22 (pictured above) didn't align with the plastic cutout and was causing it to bow outward pretty significantly. Just lobbed off a little extra plastic to provide clearance.
Covered the holes with Kaptop tape so it can slide in/out without anything getting caught up inside the DS.
View attachment 270384
Thought I'd share in the event this helped out anyone else.