Electrum ABC 5.4.2

• Enable downgrading of Trezor firmware (D17482).
• Increase the timeout for entering bootloader mode when installing
  custom firmware on a Trezor device, as the previous duration can be
  insufficient depending on USB connection speed (D17843).
• Handle a potential LibUSB error during session closure when
  transitioning to bootloader mode. This error does not impact the
  firmware installation process, so it no longer prevents firmware
  installation (D17844).
• Fix an error that occurs when opening the Trezor Settings dialog
  while the device is locked (D17845).
• Add eCash native support to Trezor One (D17770).