Installing Cosmic Desktop

Bluetooth issues

This output is useful. Your PC has a Realtek RTL8852BE Wi-Fi/Bluetooth combo card:
```
Bluetooth: 0bda:b85b Realtek Bluetooth Radio
Wi-Fi:     RTL8852BE PCIe 802.11ax
```
That specific Bluetooth ID, 0bda:b85b, has had Linux driver/firmware issues. It was specifically added to the Linux Bluetooth btusb driver for the Realtek RTL8852BE Bluetooth part, and Realtek RTL8852B Bluetooth firmware files are maintained in linux-firmware, so kernel/firmware version matters here. (Patchew)

1. First, get the missing diagnostic output

Your dmesg command failed because it needs sudo. Run:
```
uname -r
ls -l /lib/firmware/rtl_bt/rtl8852* /usr/lib/firmware/rtl_bt/rtl8852* 2>/dev/null
sudo dmesg | grep -i -E "bluetooth|btusb|btrtl|rtl|8852|firmware|hci0|opcode" | tail -160
```
That will tell us whether the Realtek Bluetooth firmware is loading correctly.

2. Update/reinstall the Bluetooth firmware and BlueZ stack

Run:
```
sudo apt update
sudo apt full-upgrade
sudo apt install --reinstall linux-firmware bluez bluez-obexd
sudo reboot
```
After reboot, try Blueman again:
```
blueman-manager
```
3. Try pairing with Wi-Fi temporarily off

Because this is a Realtek Wi-Fi/Bluetooth combo chip, test pairing with Wi-Fi disabled:
```
nmcli radio wifi off
sudo systemctl restart bluetooth
blueman-manager
```
Put the Bose in pairing mode and search again.

After the test, turn Wi-Fi back on:
```
nmcli radio wifi on
```
4. If it still does not discover anything

At that point, the practical fix is likely one of these:
1. Use a newer kernel/firmware stack.
2. Replace the internal Realtek Wi-Fi/Bluetooth card with an Intel AX200/AX210 card, if your PC supports it.
3. Use a small Linux-compatible USB Bluetooth adapter.
For now, please paste the output from step 1. The key thing I want to see is whether rtl8852bu_fw.bin, rtl8852btu_fw.bin, or a related Realtek firmware file is loading correctly or failing.
Second step

Your diagnostics show the Realtek Bluetooth firmware is loading correctly:
```
Bluetooth: hci0: RTL: loading rtl_bt/rtl8852bu_fw.bin
Bluetooth: hci0: RTL: fw version 0x42d34e04
```
So this is probably not missing firmware. The problem looks more like the Realtek RTL8852BE combo card is scanning unreliably. The Wi-Fi driver also shows:
```
rtw89_8852be ... timed out to flush queues
```
That points to the Realtek Wi-Fi/Bluetooth combo chipset acting unstable.

Try this next.

1. Do a full power reset

Do not just reboot.
1. Shut down the PC completely.
2. Unplug power.
3. Hold the physical power button for about 20 seconds.
4. Plug power back in.
5. Boot again.
6. Turn Bluetooth off on your phone so the Bose cannot reconnect there.
7. Put the Bose in pairing mode.
8. Try Blueman again.
2. Test with Wi-Fi fully off

Run:
```
nmcli radio wifi off
sudo systemctl restart bluetooth
blueman-manager
```
Then search for the Bose.

After testing, turn Wi-Fi back on:
```
nmcli radio wifi on
```
3. Try a lower-level Bluetooth scan

Run:
```
sudo btmgmt power off
sudo btmgmt bredr on
sudo btmgmt le off
sudo btmgmt power on
sudo btmgmt find -b
```
Put the Bose in pairing mode while find -b is running.

If the Bose appears there, copy the device address and pair it with:
```
bluetoothctl
```
Then:
```
pair XX:XX:XX:XX:XX:XX
trust XX:XX:XX:XX:XX:XX
connect XX:XX:XX:XX:XX:XX
```
4. My practical recommendation

Since your phone connects to the Bose and your PC’s Realtek adapter loads firmware but discovers nothing, I would not spend much more time on the internal Bluetooth card.

The most reliable fix is either:
- use a small Linux-compatible USB Bluetooth adapter, or
- replace the internal Realtek RTL8852BE card with an Intel AX200/AX210 Wi-Fi/Bluetooth card, if your PC supports replaceable M.2 Wi-Fi cards.
For now, try the full power reset and the Wi-Fi off test first. Those are the two most likely no-cost fixes.