WLED 2812B LED Strip Controller: LED don't respond after firmware update + factory reset

Hello,

i have a WLED 2812B LED Strip Controller (LS2812B-WLED) with a WS2812B RGB LED strip.

Everything was working fine. I could open the web ui and use it as normal. All animations were running.

I connected it to home assistant. Home assistant did a firmware update to v0.14.0-b3 "Hoshi".

I have had a little bit trouble with home assistant so i deleted the WLED from home assistant. After that home assistant didn't find the WLED anymore. I read a little on the internet and found a forum post, where a factory reset was suggested.

So I did a factory reset.

After that I have had problems with the WLED web iu.

I got an error: "Syntax Error: JSON.parse: unexpected character line 1 coloum 1 of the JSON data"

This error doesn't occur any longer since i set up the wifi credentials.

But:

I cannot control the LED strip anymore. None of the settings has an affect to the LED. No Colour change, no on/off, no animations. The hardware button does not work even.

If I restart the strip controller or replug it to power, then most of the time the first led is turned on. Sometimes more than one led is turned on. But I cannot change any led ba the web ui.

If I try to do a firmware update/downgrade with "WLED_0.14.0-b3_ESP02.bin" or "WLED_0.13.3_ESP02.bin" I get an error: "Update failed! Please check your file and retry!"

What can I do to get the strip controller running again? Do I have to change some settings manually after a firmware reset?

Is not the factory reset the problem but anything else?

Which firmware do I have to use for an update? (ESP02?)

Thanks in advance.