Account takeover

Allow for an account to be taken over. This is useful if a comma is sold and the seller didn't deactivate the account. Most times they do... but sometimes.... Oooooohhhhh - you sonofa-

Sometimes they don't.

Process might look like:

1. Enter existing serial number
2. Send email to existing owner saying "Someone is trying to register your comma 2/3/4 online? This you?"
3. Option to click 'I don't own that dang thing'

Something like that.

Options to prevent spam and allow for a mitigation process should be in place. Obvs.