Hey, OK! It sounds likes it is flying on 3DR firmware now. When you power up the controller and shut down it will say OPENSOLO right on the screen, can't miss it.
The controller delays shutting down after the long push on power. About a minute delay, normal.
To land, press and HOLD the fly/land button.
What you experienced was the RTH (Return To Home) - it shoots up, then works it's way home - great in a wide open area-but iffy if there are lots of trees, etc.
All that action, how high it shoots up, what to do on a RTH (land, hover in place, RTL), and other setup actions (parameters) can be customized using Mission Planner.
Just for grins, when you're done flying tonight, install Mission Planner on your PC. Accept the defaults. Inside, props off, power up and let them connect. After it advances past Waiting For Solo,
open your PC WiFi list and you should see the Solo access point. The catch phrase for that access point is "sololink", all lower case. Then, in Mission Planner, upper right boxes, select "UDP". If solo doesn't connect in about 15 seconds, hit "Connect" with UDP as the source.
Fool around with it. Under the big HUD display on the left, there is a row of action tabs. Hit "Messages" - among other things the firmware revision will show up...
Careful with the old batteries!
Mission Planner:
Mission Planner Overview — Mission Planner documentation
John