MacBook Pro error -2100D

That -2100D error isn’t particularly documented, but usually means Internet Recovery is having issues connecting to Apple, which can be a sick Mac, or potentially some local networking issue or DNS-related error or local Wi-Fi router error.

If you have the dongles or if this MacBook Pro is old enough for an actual RJ45 jack, try using a wired connection.

Or use another local Mac that can run OS X 10.11 or macOS 10.13 or whatever the latest macOS compatible with this Mac, and build and use a bootable installer.

Only notes I have on -2100

error "2100f" was reported when i had my 1st and 2nd DNS server setting set to use openDNS in the router.

https://cleanbrowsing.org/guides/manually-change-dns-on-a-mac-terminal/

Manually Change DNS on a Mac (Terminal) - DNS Content Filtering (cleanbrowsing.org)