Settings are inherited, though I don't think this would work here, but you can give it a try.
You could try adding 2 rows to the company_settings table.
1.
key: maintenance_mode
value: true (or false)
2.
key: maintenance_reason
value: We are currently undergoing maintenance (or whatever you want it to say)
Make sure the company_id is correct, and encrypted is 0.
Try this at your own risk, I'm doubtful it will work.