Replacement key for a Heybike - found.

[Mr.MikeB]

My Heybike Mars has two extra keys. The key is a 1642 ILCO blank. Heybike does not sell keys, so a real locksmith can cut a new key with that blank. I'll assume they other models of the Heybike use the same key. Possibly even different makes of bikes that use that same style battery. You can buy the blanks on-line if your locksmith does not carry that blank. Bring the battery to make sure it works !