Startup

Here is what the different screens mean. Sounds like it may have a firmware lock on it and I'm afraid now that you aren't getting responses from the person who sold it, it may be that they don't know it and knew it was doing this and they won't respond because your have been taken advantage of. If your Mac doesn't start up all the way - Apple Support

Here is an article that may help.

• Set a firmware password on your Mac - Apple Support

What model is the MacBook Pro? If it is an older model, it may not be able to use the Command + R Internet recovery and will need to have some sort of install media created for it to be able to boot off of to get it working again. Did it ever work and just start doing this or is this what you got when you purchased it from that person. If it's done that from the beginning, the Lock Pad symbol could be that it is iCloud locked and is not going to let you do anything with it because it was not theirs to sell.