Hello Craigofkirkby,
After reviewing your post, it sounds like the MacBook Air has an x in the Wi-Fi symbol and is not able to turn on. Since the symbol is there it might be a software issue where another software may be interfering. It could also be something where the hardware is not being recognized and an SMC reset may help it be recognized correctly.
Thank you for using Apple Support Communities. Have a nice day.
After reviewing your post, it sounds like the MacBook Air has an x in the Wi-Fi symbol and is not able to turn on. Since the symbol is there it might be a software issue where another software may be interfering. It could also be something where the hardware is not being recognized and an SMC reset may help it be recognized correctly.
Use safe mode to isolate issues with your Mac
How to reset the System Management Controller (SMC) on your Mac
Thank you for using Apple Support Communities. Have a nice day.