I had a similar battle with the update. While I’ve done many firmware updates on a lot of different equipment, this was the first firmware update I’d attempted on the Form 1. I found the process just a bit less friendly than other systems.
Some sort of indication on the display that the machine was in DFU mode would be really useful. As it is, there’s no apparent difference between the Form 1 in its “off” state and the Form 1 in the “DFU” state.
After much experimentation, I discovered that I needed to leave the Form 1 off for about 5 minutes, and then do the power on with the button held thing to get it into DFU mode.
Once the machine was in the DFU state (and once my computer had stopped complaining about not having drivers for the “Form 1 DFU device” that it now saw attached), the update itself was no problem.However, the machine looking the same when it finished the update and powered off as it did when it was in DFU mode, was not reassuring. Not knowing for sure that the firmware update had really finished and having seen too many items that have been “bricked” by the owner powering it off during the update process, was not a good feeling. It was quite a while before I found the courage to hit the power button.