There is actually a hard reset procedure, you might try this as an absolute LAST resort:
http://www.djiguys.com/Forum/viewtopic.php?t=3613&p=19063
And another thread on this:
http://www.helifreak.com/showthread.php?t=608810
I am thinking the new firmware is the key to getting recognition of the GPS Pro Plus module. Try upgrading without the GPS module plugged in. If that doesn't work, try upgrading one component at a time, If that fails you might try another computer (PC rather than mac). Maybe you can borrow a...
I would make sure it is on canbus 1, if that doesn't work, backup your configuration and reset to default. Then try upgrading. Once you are up on the latest firmware hopefully you can restore from the backup. You may have to unlock the controller after the upgrade too. No guarantees, just my...
Well, I sent my A2 GPS module in via the trade-in program to DJI in California. They said I should have the new one in about 2 weeks. Out of curiosity I thought I would see if the A2 could be flown without a GPS module in ATTI mode (I obviously have no patience). Motors would not start. The...