Endpoint not comunicating to Sophos Central

Ok, so I have some devices on my organization that don't show up in Sophos Central.
I've already made some research on how to fix this issue, but there are some concerns:

1 - they've been deleted for more than 90 days, so I cannot recover their passwords for desabling Tamper Protection.
2 - I dont have phisical acess to the device itself, so I cannot enter advanced start-up as mentioned here: support.sophos.com/.../KB-000036125

Is there any other workaround for making these devices communicate to Sophos Central again?

Thanks in advance.