Here is how it works - it been given to me by Entourageedge support, and I promissed to not share that, but now - once they do not exist anymore - it might be helpful for all.
The pin out from DB-9 -> 3-pin connector is:
Pin 2 -> Pin 1
Pin 5 -> Pin 2
Pin 3 -> Pin 3
This is a common pin-out for many console interfaces so most likely your cable should work.
We can use any terminal software for the PC such as Procomm or Hyperterm for a Windows system or Minicom on Linux. Our communications settings are:
1 stop bit
hardware flow control off
software flow control off
The 3 pins come out of the board but are bent to face the top edge of the device in the same direction as the mini-USB port. Pin 1 will be the leftmost pin but the serial connection will not be damaged if you accidentally plug the serial cable in the wrong orientation.
And short procedure to repair Edge bricked during update (I don't know if it works with PE):
Reconnect AC power to the eDGe and press the power button. Check to see if any text is displayed in your terminal software. If you do see text you should see a prompt to 'hit any key to stop autoboot'. Press any key to drop into the boot prompt.
From here we can enter the following two commands:
>> setenv reboot_cmd
At this point we can power off the eDGe and it should start normally at the next boot.