Thank you for the service log. We will check it if we can find a cause for the problem. In the mean time, please do also try to update using the other phone.
Attempting to pair to another phone has risk of losing the existed pair connection. Does the bootloader specifically support the BT re-pairing function? If not, I’d suggest to first wait for your diagnosis of the log.
As long as it is in bootloader, you don’t need to pair.
And all our product can store pairing information for multiple phones. So when you pair with a new phone, the old one is also still able to connect without repairing (as long as you do not change or reset the pincode using the new phone).