I had a fairly major crash (cause unknown) and have been working through diagnosis and recovery tasks. Intermittently, as I'm looking after my wife after an operation, but when time allows. I'll need to move everything to a new body shell as one arm was badly bent, but I want to get it to the point where everything works and it looks like it would fly before I start moving over. Gimbal and camera are detached at the moment - they LOOK like they survived but we'll get to those later. Immediately after the crash it would power on then immediately off during the self-check. All four ESC showed signs of bubbling on the mosfets so I replaced them all. It now powers up and stays up. It does not respond to a CSC (no props attached). Next step is to connect to the Phantom Assistant and recalibrate everything - could that explain why it doesn't CSC ? A friend suggested I ask on the forum if anything needs to be done after replacing ESCs to zero them ? As always, very much appreciate any help - thank you.