iMac services follow the same protocol as any other product service. The first thing you need to do is to locate an Apple authorised service provider and most of your problems will be solved. Contact them and discuss your issue or get your device examined by them. Apple authorised service providers receive special training from Apple, which is why they can handle any situation that you bring to them. Another option you have is to book an appointment at an Apple store or contact Apple and ship it to an Apple Repair Center. Depending on where you get your iMac services from, you can check the status of your services. Your device will be sent back to you as soon as possible.
The costs depend on what you have to get repaired and if that's covered by Apple Warranty or consumer laws or not. If Apple Warranty and consumer law do cover your repairs, then you will not have to pay a dime. If your iMac is not under warranty, the cost of repair will be different for each model and each problem. Another way to keep your iMac under warranty for a longer period of time is through AppleCare+ warranty. This basically extends the period of your warranty by three years ahead of the purchase date. The best part about this warranty is that it even covers accidental damage! And not even one but two incidents of accidental damage to your iMac will be covered free of cost. If you haven't purchased AppleCare+ warranty then you can purchase it sixty days after you bought your iMac. This warranty is very beneficial as you can save up to 200 dollars on a single repair. There are service charges applied but the iMac service costs are fully covered.
Battery issues are often covered by warranty as well. Mostly, by just following some simple steps, you can improve your battery’s performance. If you are unable to turn the screen on and it's black, then you simply have to push the power button and do some checks. Any service appointments can be made directly but for your ease, you can ask an Apple Authorised Service Provider to do so for you.