There are no longer any DangerOS devices. If you had a former DangerOS device, it is now dead hardware from the point of view of running DangerOS. You could buy one and look for a serial JTAG access and then hope for a root exploit -- I suspect that the boot process was not locked in any real way -- but you would have:

- a device with an extremely old battery

- without an open or available SDK

- with a pathetically slow CPU by modern standards

- with a pathetically small amount of RAM by modern standards

- with a mediocre keyboard under a screen with a nifty magnetic hinge mechanism but terrible specs (again, by modern standards)

- with, if I recall correctly, a very low speed GSM data connection

There's no reason to try to resurrect them.