Hello shrurhi,
Thank you for using Apple Support Communities.
We understand that your MacBook Pro is not completing the startup process. It is hanging at a black screen with what appears to be a representation of the Magic Mouse. The computer appears to be asking for you to connect or turn on your Bluetooth mouse. The first thing to check is that your mouse is connected, turned on and has charged batteries.
After checking the mouse, if the computer is still not starting up, then you will want to take a look at the following support articles to sort out what may be preventing your MacBook Pro from starting up.
If your Mac doesn't start up all the way - Apple Support
If your Mac doesn't start up as expected - Apple Support
Best regards.