If I remember correctly the flashing LED indicates a ROM error. Use a torx screwdriver to open the Amiga 500 case , pull the RF shield off and reseat all the chips on the Motherboard. (Please take Static precautions).
It's probably either the Fat Agnus (Square Chip) or Kickstart the has become unseated during shipping.
IIf you had a Monitor connected the Screen would be a Red Colour.
Cheers
Shaf
