Uhhh That The Hell happen to this poor animal Back.. are those bite or burn scars ?? Edit: (ok read whole post i see burn....)
Could be some melamine disorder.... or could be super pastel or Vanila Pastel...
Make sure You provide him right living condition temp and humidity and nutrition wise wait few sheds and then maybe this animal will start looking more normal...
^ That was also my first guess when looking at him and reading the information. I don't see a super pastel but possibly a vanilla pastel. Good luck with him and hope he's none the worse for the experience, what with his scarring and whatnot. Poor guy.