Failed firmware update to 4.16.6 on N150

Hi, I was kind of forced to do a firmware upgrade on my N150 to 4.16.6 ("Do you want to upgrade now or in 24h?"). I agreed and the update was carried out. After a significant amount of time (>3 hours), with continuous internet connection and no power drops, the Powernode still was not visible for the app, but it could be seen on my network. I have powercycled the device but no luck. Reading all kinds of posts on this forum, I connected the Powernode with ethernet cable. Still no luck. I decided to do a factory reset (30 s press of the play/pause button at start). After this reset, it cannot be seen anymore on wireless (logical), but it suggests that a hotspot is started, but no hotspot can be found. When connecting wired, and I do a power cycle, I get:
- a short brief solid red led
- then a solid green led
- then after a few seconds a solid red led
- then I hear the speaker relay clicking
- then the led starts blinking red/green (activity on the ethernet port leds)
- then the led goes solid green again. I can see the Powernode on my network with proper IP address, but the app cannot find it. There is still some activity on the ethernet leds.

When doing the same wireless, then the led stays solid red after the speaker relay click.

How can I recover from this situation?