My computer isn’t working. I may have gotten water in it. Suggestions?

Accidental damage has never been covered under traditional AppleCare.

Complaints like yours have resulted in a different AppleCare program today than the one available when you bought your Mac. In the US, this has been in force for about two years.

The new program is called AppleCare Plus. "Defects in materials or workmanship" is still covered for free.

AppleCare PLUS also includes up to two 'incidents' of accidental damage included. Screen damage falls into the US$99 deductible category. Major damage such as severe falls or liquid spills falls in the US$250 deductible category.

Details here:

AppleCare Products - Mac - Apple

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Turn it off and bring it into a Genius Bar for inspection. If you did in fact get water damage, expect a pricey repair bill.

Genius Bar Reservation and Apple Support Options - Apple

If you get a battery icon with a lightning bolt, does that mean you have a background and a working mouse and can USE your Mac, or is it the battery and lightning bolt on a blank screen, and nothing more works?

Why buy another Mac if the corporate entity excludes my machine when it’s damaged?

It isn't just Macs - this applies to ALL manufacturers of laptops/computers. Laptops and some other electronics are not expected to be waterproof. The owner of the laptop is responsible for such damage.

https://www.cpscentral.com/what-is-and-isnt-covered-by-a-standard-laptop-warranty/