Crawlability, indexation, and ranking are three separate diagnostic layers.
First ask whether a search engine can fetch the page.
Check status codes, robots rules, links, rendering, and logs.
If fetching works, ask whether the engine kept the page in its index.
Check canonicals, duplicates, soft errors, and page value.
Only after both layers pass should you investigate relevance, authority, intent, and competition.
Fixing titles cannot solve a blocked crawl.
Resubmitting cannot make a weak duplicate rank.
Diagnose in order.