---- Replacement F2 FuseDigikey:
I had the same problem until I properly cleaned the power switch. This involves removing the metal cover (soldering iron needed) and cleaning the contacts inside. I've had the "black screen on boot" issue exactly once since the post, however that was when the battery was on low power so it was probably tied to that. I also bought a second kit directly from FP to mod a second GBA as a gift and didn't run into any problems with it during testing (and haven't heard of any problems from the recipient; they See my video on the non-laminated version:
So I made a u-turn and came back home. I noticed the light goes out completely at idle. Nothing. It only flickers while driving. With the engine running I yanked out my multimeter real quick and checked the power at both battery terminals. Both showed 13.95 volts. Checked at the alternator, showed 14.12 volts at idle.
What's very worrying about flickering (for the bottom screen) is this usually indicates unsteady power delivery either due to external influence or internal hardware failure. One of the sucky things about LCD screens is that they can be affected by electromagnetic interference if they're not properly shielded.
In a sense, yes. The battery is likely instead of cleanly and linearly going down in voltage is possibly falling down steep, skipping the voltages the SP is calibrated to run the red LED rather than green. For example, full cell is at 4.2v and dead is at 3v (these may not be fully accurate for the SP). If the SP was set to trigger warning St 3

Battery and fuses are good. So, i got second hand AGS-001 that's not powering on at all and won't charge. Green light doesn't come up when I flip the switch. When i'm connecting a charger, orange light comes up for a second and then disappears. When I opened it up, there was some corrosion in the start/select buttons area and by the F2 fuse.

The flickering LED could be a sign of a dirty power switch. This seems to be a common problem with old GBA units (including the GBA SP). I could be mistaken, but there is no real solution except to open it up, de-solder the exterior component of the power switch, and clean it out with some isopropyl alcohol. H27z.
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    • gba sp battery light flickering