GBA Start Button not working

[regal sky]

Select works fine; all the other buttons work fine. Start and Select both have continuity with the big block on the lower-left corner of the CPU, but only the edges of the button contacts, not the center. Best I can guess is that there's something wrong with the membrane, but I've tried cleaning it off and I've tried really ramming down on the start button with a screwdriver and I still can't get the system to recognize the keypress. I can try with a different membrane, but otherwise, what are my next steps?

[viral narwhal]

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Because this post has the "Game Boy Advance" tag, we recommend checking out this wiki page https://gbwiki.org/en/consoles/advance

[shrewd iron]

The GBA uses common ground buttons, so some contacts on each button pad are connected to ground, and others are the actual signal line for the button -- for start and select, the center contacts are the signal lines, which is why you don't get continuity to the gold square near the CPU(that's ground). Do you get continuity from the center contact on start to TP3? That pad looks a bit toasty

[regal sky]

I'll check, but that's mostly the LED strip. Which test pad does Select go to?

[shrewd iron]

TP2

[regal sky]

TP2, apparently. I do get continuity between Start's center contact and TP3. I also get continuity between the center contact and one pin on the CPU.

[shrewd iron]

Now check for continuity between TP2 and pin 127 on the CPU -- should be second from the bottom on the left side

[regal sky]

There's continuity between the center Start contact and the second pin from bottom on the left, and continuity between the center Select contact and the third pin from bottom on the left.

Similarly there's continuity between TP3 and the second pin, and TP2 and the third pin

Tried a different set of membranes; same result.

[shrewd iron]

That all sounds normal so far. To be clear, the start button doesn't work at all, or it just doesn't work with the LED controls?

[regal sky]

Doesn't work at all.

I had a theory that maybe it was always being pressed - was testing with SMW - but that doesn't seem to be the case. I dug out my old EZFlash IV and stuck a button tester on it. It isn't showing that the button is being pressed.

[shrewd iron]

If it was always being pressed, the center contact would have continuity with ground

[regal sky]

Or the membrane would just be too large and was always touching the contact.

Point is moot though, btntest.gba doesn't show an X next to Start.

Anyway, it's getting late and I'm going to a friend's kid's little league game tomorrow morning, I should get to bed

[shrewd iron]

Not sleepless in Seattle this night?

[regal sky]

Afraid not :/ Sides, I'm getting too old to stay up all hours.