You need to turn radio off. Then press the lower left function button and power up. That will put in program mode.
I also had a voltage problem with the 730 series. I needed to have the vehicle running to up load and down load.
On the alpha head, i am not sure which button you depress while powering up. The basic head it is the lower left button. May be same on the alpha, but memory lapses on that one. Try themm all.
Also, when you get through reading, the display (basic head, not sure about alpha head) will show "EN" instead of "PC" like it did to begin with. While it displays "EN", you can not write back to the radio after you make your changes to the codeplug. Pressing the "D/A" button (lower right on basic head) will revert it back to "PC", and you can now write to the radio without having to turn it off and back on again.
Brett Kitchens
KF4SQB
kf4sqb "at" wetsnet "dot" com
Of all the things I've lost, it's my mind I miss the most.......