PIONNER AVH-X7800BT Bluetooth Connection Issue: Connected Without Phone, Restore Settings

Hello ?
A few days ago I bought a PIONNER car radio, model AVH -X7800BT and since yesterday I have a problem with connecting via Bluetooth.
The truth is telling at the very beginning I paired the phone with the radio normally and bluetooth worked, but after trying to connect the phone with the radio again, the Bluetooth connects, however, it shows 'connected without a phone' and still nothing works.
I tried to remove the paired devices, but I do not have such a possibility because the BT function is not illuminated as if the radio did not have such a function. I also wanted to try to restore the factual settings through 'RESTORE SETTING', but this option is also not highlighted and I cannot enter it.
Or maybe someone has encountered a similar situation or knows how to reset this radio in another way? HELP

Disconnecting from the power supply does not reset the settings?

I tried by disconnecting the cubes and then the same, I was supposed to try to disconnect the battery but I don't know if it would help at all .. I thought there was maybe some other way to restart.

See if you have a hole in the OPEN button, there is a reset button inside, you need to press it with a straightened paperclip or similar tool.

Ok radio, I restarted the phone connected to Bluetooth, but still without a phone and I do not have a phone book, in addition, I am sending a picture where the BT icon is still not lit and I cannot enter it

Maybe the problem is in the phone settings - check on the phone if there is an available player in the car on the BT list and if the permissions are not blocked there.

I checked but I'm afraid I can't check it

Added after 11 [minutes]:

Honestly, I looked through the whole phone but I can't find anything like that ...

What kind of phone is it?

Huawei p10 - when I enter BT there are no settings. I downloaded the appradio application, but it is for ISO 7.0 and I have Android 7.0. I thought that somehow I could connect it with a cable and try the program, but nothing too.