Yeah, I think you're going to have to send it in for repair at DJI.
Yours isn't exactly the same as mine (I had no device detected at 0800 as well) but the 1500 error is the same.
Can you tell me? Did you have the transmitter switched on while you were upgrading the aircraft? This seems to be the cause of these failures with the Inspire Pros from doing a fair bit of reading and collating of information around the web.
2 things to try though. Clean the contacts on the gimbal and aircraft where they connect together and check the ribbon wires are plugged in securely.
DJI repaired mine for free even though it was well out of warranty. You may be lucky.