Sony home theatre system

Question

my sony reciver is flashing ;protect' after have an extension cord short out. i have unhooked all speakers and unplugged the reciever,still in protect mode. my husband and i were painting and we have a tv installed on the wall, when i moved the system back, a cord shorted out! have i fried the reciever? have done everything i have read and nothing is working! the model # is-sony str-k900. thanks in advanc for any help