I have a 2004 ford escape I let the battery die, and now the radio has no power

Did you replace the battery or recharge it? On many newer vehicles if the radio looses power for what ever reason you must reenter a security code to get it to work again. Check your owners manual for directions.

Sounds like your radio needs to be coded. If it is a factory installed radio, it could be easily fixed by calling the manufacturer of the vehicle. If the radio is aftermarket, there is a number of ways a radio can be coded-A certain CD must be put into it... a certain sequence of buttons be pushed... a numeric code be entered. This happens to render the radio useless if it is removed from the vehicle. You lost power to the vehicle, so as far as the radio is concerned, the radio was removed. It is just doing its job. To tell if it is aftermarket or not, typically an aftermarket radio will be named, like Alpine, Sony, Panasonic... if it is aftermarket, look up the model number and make on line and see if you can find directions on how to get it to work again. Hope this helps