Macbook Pro Bluetooth not available after plugging in a dongle I plugged in a USB Bluetooth dongle into my MacBook Pro 16" late 2019 model and it seems that after unplugging the dongle I am unable to use my Macbook's internal Bluetooth controller. I am not able to connect to any BT device when the dongle is not connected to the Macbook.

Here is my System Report for Bluetooth:

  Apple Bluetooth Software Version: 7.0.4f6
  Hardware, Features and Settings:
  Name: Aleksanteri’s MacBook Pro
  Address:  3C-22-FB-05-56-D9
  Bluetooth Low Energy Supported:   Yes
  Handoff Supported:    Yes
  Instant Hot Spot Supported:   Yes
  Manufacturer: Broadcom
  Transport:    UART
  Chipset:  4364B3
  Firmware Version: v50 c4177
  Bluetooth Power:  On
  Discoverable: On
  Connectable:  Yes
  Auto Seek Pointing:   On
  Remote wake:  On
  Vendor ID:    0x05AC
  Product ID:   0x0096
  Bluetooth Core Spec:  5.0 (0x9)
  HCI Revision: 0x1051
  LMP Version:  5.0 (0x9)
  LMP Subversion:   0x2032
  Device Type (Major):  Computer
  Device Type (Complete):   Mac Portable
  Composite Class Of Device:    0x38010C
  Device Class (Major): 0x01
  Device Class (Minor): 0x03
  Service Class:    0x1C0
  Auto Seek Keyboard:   On
  Devices (Paired, Configured, etc.):
  Magic Trackpad 2:
  Address:  E4-50-EB-F1-5F-81
  Major Type:   Peripheral
  Minor Type:   Trackpad
  Services: 
  Paired:   Yes
  Configured:   Yes
  Connected:    No
  Bluetooth Core Spec:  1.0b
  Vendor ID:    0x004C
  Product ID:   0x0265
  Class of Device:  0x05 0x25 0x2594
  Services:
  Bluetooth File Transfer:
  Folder other devices can browse:  ~/Public
  When receiving items: Accept all without warning
  State:    Disabled
  Bluetooth File Exchange:
  Folder for accepted items:    ~/Downloads
  When other items are accepted:    Save to location
  When receiving items: Accept all without warning
  State:    Disabled
  Bluetooth Internet Sharing:
  State:    Disabled
  Incoming Serial Ports:
  Bluetooth-Incoming-Port:
  RFCOMM Channel:   3
  Requires Authentication:  No


What have I tried to do to fix this:


Restarted the computer numerous times
Deleted /Library/Preferences/com.apple.Bluetooth.plist file
Reset PRAM, NVRAM and SMC
Ran bluetooth with Debug mode to "Reset Bluetooth Module" and "Remove all devices"
Installed Bluetooth Explorer that shows the following error on startup:


updateChainPower error: -3903
2020-04-13 20:35:57 +0000 Apple80211Get(APPLE80211_IOC_BTCOEX_MODE) returned error -3903
updateChainPower error: -3903


Bluetooth starts working again when I plug in the dongle. Have I broken the internal controller by attaching an adapter to the machine? I am not even able to connect my Magic Trackpad to the Macbook via Bluetooth. First, I pair it with the machine using the cable. After disconnecting, it is unresponsive and is not able to connect.

What are my next steps? Is this a warranty issue?

EDIT: This is the dongle that might have caused the issue: https://www.aliexpress.com/item/32686102148.html

EDIT2: Took it to the repair shop today, I'll follow up with what was the resolution of that case.

Strangely enough, they advertise that it does not work with Macs but now it is the only way to get Bluetooth working on the Macbook.
This seems to be a general problem with motherboards of 2019 models.
Check this link:
https://discussions.apple.com/thread/250944058
There are many people including myself that has this problem.
It seems like the only resolution to the problem is a motherboard replacement.
I have exactly the same error and problem.
I used a dongle that supports mac.
Just for information:
I have tried to reinstall, clear t2 chip using xartutil --clear-all, nvram reset, smc reset and so on.
Seems motherboard replacement is the only resolution.
Update: A new method to fix this problem has been revealed on the apple forums: https://discussions.apple.com/thread/250944058