Migrating BE 2014 to BE 21 on a new server problems

We are currently running Backup Exec 2014 on a Windows Sever 2008 R2. We need to decommission that server and migrate BE to a new Windows Server 2016. We are aware that BE 2014 will not run on Server 2016, so we are looking for the most effective/supported method of migrating. We’ve tried the Migration Assistant, but that will only go from Be 2014 to BE 20. Having Installed version 20, the migration fails on source database credentials and incompatibility. Trying the manual migration method, the copying of the database via beutility appears to work but then errors when attempting to start the services, leaving us with an inoperative system. We tried installing BE 2016 but that fails to open. We’ve tried all installs/migrations etc through various administrator/domain admin accounts and get the same errors each time. Have we any options left? Is there a recommended\foolproof method of migrating our current Backup exec catalogues\data\jobs etc to a more up-to-date and supported version compatible with Windows Server 2016? Has anyone else attempted this, and found any workarounds?