Based on
- https://forums.serverbuilds.net/t/aruba-ap-to-iap-conversion/8888
- https://localsharespace.com/convert-aruba-ap-315-to-iap/7/
- https://karubits.com/posts/Converting_Aruba_AP_to_IAP/
Connect serial TTL cable, power on and wait for the Hit <Enter> to stop autoboot:
prompt