If after scanning the admin's pairing code, the machine proceeds to the 'Sorry, we're down' screen, it indicates that it's successfully paired and we should focus our attention to server-side settings.
First, the screen may be caused by having enabled coins in the admin whose wallets have not yet been installed.
Navigate to the admin's 'Maintenance > Funding' panel and click on each coin's tab. Does the deposit QR code appear for each one? If not, and a 'networkError' message instead appears, it's a sign that that wallet hasn't yet been installed.
Use the article Setting up your wallets in order to install wallets and properly configure them.
Machine needs updating
Machine and server versions need to be in concert to be compatible with one another. After receiving your machine, we recommend arranging an update to ensure you have the latest machine-side software.
Older or second-hand machines will definitely need updates to be compatible with the server software that's currently installed through the setup article.
Use the article Determining your machine version to retrieve the information that will help our support team locate and update your machine.
If the above doesn't resolve
Should the above two sections not address the 'Sorry, we're down' screen, please collect server logs so we main gain further insight into the status of the server.
Run the following four commands individually within your server:
tail -50 /var/log/supervisor/lamassu-server.err.log
npm -g ls lamassu-server
su - postgres -c "psql \"lamassu\" -Atc \"select * from devices\""
Then, please copy the results (as text) and supply them to our support team in order for us to better research the situation.