Hi,
I've done this task tones of times for my clients. It won't take too long and I'll only need a computer connected to the AP via a console cable, teamviewer running on the laptop and a tftp server running locally, such as the free Solarwinds TFTP server (or the AP with internet access so I can use my own tftp server).
Alternatively, if the AP is in lightweight mode and connected to the Wireless controller, we can push the firmware from there.
I've got over +15 years experience and I'm just getting started in freelance, so keen to win the business and gain reputation points :)
Thanks and regards
Alonso