Have you tried running some homebrew using your magic key 3 as the passme device??
You can download this homebrew app here, burn it with Neo Power kit onto your neoflash cart, and then connect your mk3 (with original game inserted) in order to see if it runs.
http://www.neoflash.com/forum/index.php/topic,1568.0.htmlNote: The SD card does not need to be inserted into the mk3 in order to do this (it operates similarly to a mk1, with just an original ds cartridge inserted). Try all your ds cartridges to test (try to avoid using Mario 64)
Also, check that the mk3 connectors/slots are all fine (there are no bent pins, tiny obstructions, etc). The "gold fingers" may be cleaned with a q-tip and a tiny amount of isopropyl alcohol.
That "option pak" notice also pops up when the original nds cartridge and/or the mk3 itself are not inserted fully (properly seated) in the slots.....
BruceG
EDIT: If you can get homebrew working on your mk3, you should be able to flash the menu file onto the neoflash, and run it as well (at that point you could copy clean dumps onto your sd card, and insert your sd card into your mk3 to see if it's detected by the menu)