So I am understanding that you had a loose prop and when you took of the prop flew off and the Mavic Pro crashed as a result. When it crashed it broke the gimbal mounting bracket. There is also an error with Motor Number 2 in which the Electronic Speed Controller is or ESC is damaged.
Sounds like you have 2 issues. Broken Mavic Gimbal bracket AND either a motor failure due to crash and/or onboard electronics issue due to crash.
The broken gimbal bracket is not going to produce the error message you quoted within DJI GO 4 app. That error is specific to the onboard Electronic Speed Controller for the motor in question.
If you just want to buy the gimbal bracket and rip apart your Mavic Pro to replace it yourself you "may" be able to pick one up from @Thunderdrones on this forum.
Once you disassemble the Mavic yourself it voids your DJI warranty. They will know as there is specialized glue added to specific screws that need to be removed for disassembly.
