Troubleshooting faulty 3DS motherboards
I have two 3DS motherboards that I'm trying to troubleshoot, so that I can use at least one to replace another that's in a bricked system. One of the MBs causes the well known 'pops and turns off' problem on boot (where a few seconds after being turned on, a popping sound can be heard, and the system immediately turns off). The other board simply fails to boot, with no backlights turning on for either screen (this one does not respond to any of the 'forced' functions, such as L+R+A+Up).
I've been able to conclude that in both cases the problem is with the motherboard, as a third board was able to start with no issues in the 3DS. The cables had been seated several times to rule out those issues as well. In all cases, the SD card reader, nattery, L/R ribbon cables, WiFi card, infrared chip, top and bottom LCD, microphone, and C stick components were shared, so I've ruled them out as being causes. Both F1 and F2 fuses are shown to be working on both boards as well.
Is there anything else I could possibly test to identify a solution? I hate wasting parts if they can be saved, especially the motherboard.