DSi "The device inserted in the SD Card Slot can't be used."

As the title describes, the DSI unit I'm working on isn't able to read SD cards, displaying the following error when trying to access them via the Camera app. Here's what I've done so far:

• Replaced L/R/SD card flex cable with new cable.
• Swapped DSI backplate (with flex cable) with a known working system.
• Tried several SD cards, re-formatted both with the standard file explorer and the official SD card formatter. Can confirm full function with known working DSI.

At this point I'm almost certain it's a motherboard problem. Based on the rust in the system, (none on the flex cable contacts, mainly on the game cart reader) I'm willing to bet it's suffered water damage and now the motherboard can't read SD cards at all.

At this point I would just go ahead and perform a motherboard swap, but my client specifically wants this board fixed to get their childhood photos off the unit. As far as I know, the SD card is the only way to go about doing that, right?

Two questions:

1. Is there any chance I could fix this problem on the motherboard?
2. If not, can I get the photos off the device in any other way?

So I'm throwing in the towel on fixing the problem, but on a good note I figured out a different (albeit slow) way to get the photos off the unit. You can exchange photos over wireless within the camera app if you have another DSi. What I ended up doing was transferring all the photos from the broken unit via this method to an SD card in another working unit. I then transferred the files off the SD card to my client.