New update broke the backend

I uploaded 8.7 successfully, but when clicking activate, the screen goes white and I loose complete access to the back end. I spent an hour with my hosting company to get access back. It seems that the composer plugin might have been the issue, once we deactivated the 2.0 composer plugin and reinstalling 8.6 and the original plugin, its working again. How can I get the 8.7 update to work correctly? Thanks

Delete the td composer plugin and install the updated version that came with version 8.7. That will solve your problem. But make sure you update the theme first via FTP before updating the plugin.