Is it permissible for a person to act as an intermediary between Apple Inc. and the owner of a locked device to help unlock it in exchange for money, even though the device owner can communicate directly with the company? And is it permissible for another person to issue a non-original purchase invoice for the locked device to prove ownership and unlock it?

Firstly, there is no harm in using an intermediary to communicate with the company to unlock the device for a known fee; this is a permissible contract of ju'alah (commission/reward).

Secondly, if unlocking the device through communication with the company is only possible by issuing a non-original purchase invoice, this is permissible. This is because it is a lie to secure a right that would otherwise be lost, and it serves a benefit without causing harm to others. Lying is permissible to achieve a praiseworthy objective if it cannot be attained otherwise. It is recommended to use tawriyah (ambiguity/equivocation) in such cases, but if tawriyah is not used, the lie is not forbidden in this situation.