My hp envy dv7 7227cl has stopped working and the repair told me he have changed the bios software and the gpu chip but when came to me and i powered it the model and serial and product code all has been changed and different from all serials on the pack of my laptop under the battery. So can what he changed make that and my model says it's now dv6 not dv7 like what I know and the original serial from the box says it's dv7 7227cl. So please help me can this be true or he stole mine. Thanks in advance