Best answer by Moritz M
If there is no LED showing any indication of a working component it most likely is broken. However two things might be still something you want to consider doing.
The factory reset as mentioned by Chris already, the other thing would be, if you have another PLAY:5 or PLAY:3, to replace the power cables.
If that will not help at all please get in touch with our support via phone since we would not like to gather your address information here.