Solving Acekard 2i Contact Issues
Contact issues can prevent your Acekard from appearing in the DS menu. It can also make your DS freeze mid game or during booting. If your Acekard doesn't appear in the DS menu it is normally a slot-1 contact issue, or a bad flash. It's not the MicroSD card , your DS will still detect the Acekard even if the MicroSD card isn't inserted. You should first try unbricking you cart as in the unbricking guide above. If that doesn't work then try a paper trick as below.
If your Acekard freezes mid game, this can be a slot-1 contact issue, or less commonly a MicroSD card contact issue. If your Acekard sits on a blue loading screen when you power it on, it means it can't see your MicroSD card. You can verify this by trying to boot your Acekard up with no MicroSD card inserted, you should find it will sit there on the blue loading screen.
If you are using a DSi XL, pulling the cart slightly out of the slot after insertion has been known to work. Insert the Acekard into the XL's cart slot normally until it locks in position. Once locked without depressing the cart pull it out slightly. You shouldn't be able to pull out by much as it should still be locked in position.
If none of these methods work, you will need to send it back to your retailer for a replacement. There really is little else you can do.