garmin c510 streetpilot not booting properly?

garmin c510 streetpilot. i uploaded my own image onto the system, but recently the unit erased everything on it except the image that i put on it. i haven't put a memory card in it since it erased everything. so now i put a 5v mini usb charger in it and it comes up with the image but then it goes off when i haven't got the charger in it. when the charger is in i get my custom image and a picture of the c510 in a computer. anyone who can help let me know on 07897653176 thanks