Sound issues Archos 101 Cobalt

[Quince22]

Hello everyone, I am new to this forum, its actually my last resort for help with my problem.

I have lost the sound on my Archos 101 Cobalt tablet. The only sound that works is the 'low battery sound', but no further system sounds, nor app sounds work.

I have tried reinstalling the firmware/resetting to factory settings, tested all sound-settings. Also the headphones do not work when i plug them in.
I reinstalled the rom via original Archos software on the website specially for Archos 101 Cobalt.

Because the 'low battery sound' does work, the speaker cannot be defect. That is why I think that this is a software problem.

Does anyone have an idea or solution for me?

Greetings Quince22