Re: Power cord replacement - what model # is my Roku Streaming Stick?
There were two purple Roku Sticks.
3400 - Has only one connection, an HDMI-like HDM connector that both provides the signal to the tv and and draws its power from an HDM port (phyically same as HDMI) on the tv. There is no separate power cord. Since you're asking about a power cord, this probably is not your model. HDM ports were used in tvs for only a few years, never really gained favor, and have largely been forgotten.
3500 - Uses a normal HDMI connection to the tv and has a separate USB connection for its power. You can purchase a replacement from Roku on this page - be sure you get the one for the 3500, not the one only for the 3810. But this is just a standard USB power adapter like is used by all sorts of devices and a cord with a USB-mini connector, so you may well have what you need lying around the house. Just be sure the USB power adaptor has a rated out put of at least 1 amp.
Roku Streaming Stick +, 3810X, Ser YH0059427035, wifi - Samsung UN55ES6100
Roku Streaming Stick, 3600X, Ser 5S56D8240827, wifi - JVC EM37T