lenovo a3500 hv flash fail error 4008 sp download fail

my lenovo a3500hv stuck on logo for the third time but this time reflashing fails and it tells me download failed error code 4008 i tried every possible solution but useless. I changed cable , port, firmware and sp flashtool version. I alse sent the device to a repair center but they couldn’t fix it .:confused::confused:
please help me fixing it.:(:(