Macbook Pro mid-2012 restarts after entering password

Macbook Pro mid-2012 restarts after entering password and gives an error after restart

I'm unable to use any other boot command like Command + R etc as it leads to a screen with a lock and I've forgotten firmware password. I've even tried the trick to swap/remove rams and reset nvram 3 times, but nothing works.

How can I start my macbook?

Solution 1:

Without the firmware password you will need to take your machine to an Apple Store or official Service Provider, along with proof of ownership.

Ref: Apple KB: How to set a firmware password on your Mac

The old 'remove the RAM' or 'reset NVRAM' tricks etc only work with older PowerPC Macs, not Intel.