Which iPad do I have? Only the serial number to go on

there's also a model number on the back in tiny print, starts with an A followed by four digits. search that and it tells you exactly which iPad it is. in Settings > General > About, tapping the model number switches it to the same A number too.

put the serial into Apple's check coverage page, it shows the exact model name (generation and size) along with the warranty status. if the iPad turns on, Settings > General > About shows the model name too.