Order #6121 - Betafpv Air Brushless Flight Controller 5in1 - ESC unavailable

Order Number: 6121
Product Name: Betafpv Air Brushless Flight Controller 5in1
Brand: BetaFPV
I have attempted to change the ESC firmware on my BetaFPV air G4 5in1 FC using esc configurator.
During the upgrade process, the FC went into a ‘hung’ state and after leaving for a period of time, had to be rebooted.
When I load ESC configurator I can now only see ESC#1 and ESC#4.
I have taken several steps to attempt to resolve this - firstly I have reloaded the Betaflight default firmware from website, secondly I have used BLHelisuite to try to see the missing ESC. I have had no success. The unit has not been flown, but has had camera and motors soldered on to it. I have also tries to use several methods order when re-plugging power and USB plugs while attempting to see the missing ESC in esc configurator.