No power
Before opening anything, rule out the simple causes. If you do open the console, remove power first. Battery corrosion residue is caustic, so wear gloves if you see any.
Troubleshooting: No Power
A GBA that shows no life at all usually has a power-delivery problem, not a dead mainboard. Work from the easiest causes to the hardest.
- Check the batteries. Try fresh AAs in the original model, or fully charge an SP. Weak or wrongly oriented cells are the top cause of a dead unit.
- Inspect the contacts. Look in the battery bay for corrosion on the springs and flat plates. Clean to bright metal with isopropyl alcohol, since corroded contacts block current even with good batteries.
- Test the power switch. Slide the switch firmly fully on. A dirty or worn switch can fail to connect; a contact cleaner spray sometimes revives it.
- Look for the light. If the power LED flickers or glows faintly, suspect contacts or batteries. No light at all after the above points to a switch or board fault.
SP specifics
On the GBA SP, a swollen or worn rechargeable battery may no longer hold charge. Confirm it charges and, if not, replace the internal cell with a known-good one.
If none of these steps help and the contacts are clean, the fault may be on the board, such as a failed regulator. That is a job for advanced repair or a replacement mainboard.