Why does my system keep freezing?

My new Nintendo 3ds xl will power on but at random times between seconds and 6 minutes the screen freezes audios stop and the only thing I can do is a full power off, happens even without games on or in the console. If I place the console on an ice pack the freezing does not happen, I opened up the back and see no thermal paste, but there is a pink powder spread throughout on the inside of the back plate, but could anything else be causing it/ is there a solve with getting thermal paste?