Glad you are up and running now.
Note for anyone having the same problem here is the relevant information from the RPi document noted earlier.
So use a USB 2.0 flash drive.
Note for anyone having the same problem here is the relevant information from the RPi document noted earlier.
Quote:USB Host Boot Mode
Note
Host boot is available on Raspberry Pi 3B, 3B+, 3A+, and 2B v1.2 only. Raspberry Pi 3A+ only supports mass storage boot, not network boot.
The USB host boot mode follows this sequence:
- Enable the USB port and wait for D+ line to be pulled high indicating a USB 2.0 device (we only support USB2.0)
So use a USB 2.0 flash drive.
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bob
bob