Well, I had to ask. Sent my old A2 GPS on the trade-in program and it will be at least two weeks before the Pro Plus arrives.... Can the A2 be flown in ATTI mode without the GPS module?

Never tryed. Give a try and Report us. NAZA works without GPS module.

The LED flashes groups of 5 really quick yellow flashes (as close as I can count) and the motors will not start. So, it doesn't seem to want to fly. Unless there's something I'm missing.

When you use A2 or WKM flight controller you cannot start the motors without GPS module.

DJI-Autumn Posted at 2015-2-4 16:44
When you use A2 or WKM flight controller you cannot start the motors without GPS module.

Not correct. I have 4 WKMs and I can fly them without GPS connected with early or latest firmware.

This is necessary when we have to fly on locations with probable magnetic interference, and we don't want the magnetometer to cause trouble (even in ATTI).