It sounds like the adminconsole cluster (or possibly the whole allocator hosting it) went down, which takes the UI down with it
You can check what's going on without the UI, using the API (docs: https://www.elastic.co/guide/en/cloud-enterprise/current/ece-api-reference.html)
eg curl -u root:PASSWORD 'HOST:12400/clusters/elasticsearch' (use readonly and its password to generate a sanitized list) will list the clusters together with some basic health information, /platform/infrastructure/allocators will list the health of the allocators etc