C330 will not power up when plugged into power receptacle in car

First, check the car's power receptacle by plugging in another device that definitely works (or take your gps to another car). Cars generally have a fuse associated with the receptacle that can blow. The second most likely problem is that the internal battery inside the c330 has died. This is especially likely if the unit is old (more than 1 year) and if you live in a climate with extreme heat or cold (which reduces battery life). This video shows how to replace the battery:
The company that produced the video sells a kit which includes the battery and tools necessary to replace the battery yourself. See: http://www.newpower99.com/ProductDetails.asp?ProductCode=GARMIN+STREETPILOT+C330&Show=ExtInfo I swapped the battery of my brother's dying GPS using the aforementioned kit and all went well. His Garmin is back up and running smoothly.
Hope this helps.

In the tip of the unit there is a glass fuse that can be replaced. Please check that first. Next thing to check is the cable. If you have a multimeter put it in the continuity measuring setting. Then measure from one end of the cable to the other to make sure there is no break in the line. If you need a replacement cable I suggest GPSCity ( http://www.gpscity.ca )