VIZIO 756TXECB0TK0020 MAIN BOARD FOR M502i-B1. This board is fully tested and removed from a set with a defective Panel. First, you as the purchaser of the part is accepting the role of the technician in properly diagnosing and installing the part. We do not know your qualifications as such. Secondly, each part we sell came from a TV that had a broken or defective LCD or Plasma panel. Any questionable boards are disposed of.