Electronics are required to come with schematics, just like prepared food has nutrition facts on the package. Similar to checking whether you can digest well what you eat, schematics allow you to make an informed decision based on longevity to be expected. Likewise, you can ask others to help you out, such as your nearby repair technician, makerspace, or good friend with experience.
Is your device broken? Check out the Repair Wiki.
Do you need a connector for a board? Have a look at the connector book. It will help you figure out what the connector is called through browsing by pictures or categories.