"Connection lost to usb://0" when run Propeller Test

[r-bt]

When I try to run Prepeller test on a Crazyflie 2.0 after getting this in the console:

HEALTH: Acc noise floor variance X+Y:0.002556, (Z:0.002143)
HEALTH: Motor M1 variance X+Y: 25.54 (Z:39.99), voltage sag:0.35
HEALTH: Motor M2 variance X+Y: 1.17 (Z:0.55), voltage sag:0.34

I then get this message in a popup window:

Connection lost to usb://0: Error communicating with the Crazyflie ,it has probably been unplugged!
Exception:Crazyflie disconnected

Traceback (most recent call last):
  File "/Users/richard/Documents/SwarmUROP/Drones/.venv/lib/python3.11/site-packages/cflib/drivers/cfusb.py", line 168, in receive_packet
    dataIn = self.handle.read(0x81, 64, timeout=20)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/richard/Documents/SwarmUROP/Drones/.venv/lib/python3.11/site-packages/usb/core.py", line 1029, in read
    ret = fn(
          ^^^
  File "/Users/richard/Documents/SwarmUROP/Drones/.venv/lib/python3.11/site-packages/usb/backend/libusb1.py", line 846, in bulk_read
    return self.__read(self.lib.libusb_bulk_transfer,
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/richard/Documents/SwarmUROP/Drones/.venv/lib/python3.11/site-packages/usb/backend/libusb1.py", line 954, in __read
    _check(retval)
  File "/Users/richard/Documents/SwarmUROP/Drones/.venv/lib/python3.11/site-packages/usb/backend/libusb1.py", line 604, in _check
    raise USBError(_strerror(ret), ret, _libusb_errno[ret])
usb.core.USBError: [Errno 5] Input/Output Error

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/richard/Documents/SwarmUROP/Drones/.venv/lib/python3.11/site-packages/cflib/crtp/usbdriver.py", line 237, in run
    data = self.cfusb.receive_packet()
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/richard/Documents/SwarmUROP/Drones/.venv/lib/python3.11/site-packages/cflib/drivers/cfusb.py", line 175, in receive_packet
    raise IOError('Crazyflie disconnected')
OSError: Crazyflie disconnected

The propeller test works for other drones. I'm using the latest firmware

[tobbeanton]

This might be caused by a "brown-out". The voltage getting so low that the CF reboots? Most likely a bad battery cable, battery or the connector.