Dialog not visible

[Rutger]

I have old pair of white Phanthoms (now Phantom I 103db) from 2015 (no Airplay) with Dialog. Setup was running fine during Spark times. 2020 I updated to DOS 2 and retired Dialog. Phanthoms are running fine being ETH wired and have updated themselves to 2.14.4 in meantime.
Yesterday I hooked in again the Dialog to have one more Optical input. It worked !
Showed firmware 2.8.5 (first from 2 series what it got during initial update) and played well to Phanthoms After an hour update notification came and I pulled the trigger. Update failed after long wait !
Now Dialog powers on (some slow purple blinks and the stable white light). It gets IP from router and I can access its web interface. But Devialet app at iPhone does not show it and I can not use its optical input.

I have tried:
3 times pushing reset
10 sec holding (turn off after 3 secs)
15 sec holding (same

attemts to get it download new firmware:

On-3 secs off-4 secs on-3-4-3-4-3-on
On-7 secs offf-3 secs on-7-3-7-3-7-on
Off-7 secs on-3 secs off-7-3-7-3-7-3-on

It does not start downloading firmware. What gives ?

I had the same issue yesterday after updating.
I tried all the same things you mentioned. Also switched the unit off for a longer periode of time all without success.
When I tried to install a new device and selected my Dialog I regained access after going through the 3 times pushing reset procedure. 
It works fine now. After the adding the device it popped up and showed the latest firmware (apparently the update does work but prevents it from properly starting).
Hope this helps you too.
Rgds