What's the problem???

Hi,
I recently bought a MEGXON SAPPHIRE TX5500Z from a second hand store, when I had brought it home it worked accordingly I then added my SD card and it would not come on!, I thought the battery may just be low so I put it in the battery charging dock. When the light turned from red to green I placed the battery back in the camera and put the SD card in again, It still would not come on! Only for a green light next to the view finder.... I then took the SD card back out again, and it came on! Any answer's please do post, Thanks :)