put my iPhone 6 in a cup holder which it was upside down. In the cup h

Hi,

As you know water, and electronics and electricity are not a good mix.

The impurities in the water causes corrosion and provides circuit paths for the electricity which were not in the phone's operating design and could damage the components. The corrosion is ongoing and doesn’t stop until it has been cleaned away.

Rice does not fix the problems caused by corrosion

Rice is for dinner not repair

First do not turn on your phone and then you need to remove the battery as soon as possible from the phone to minimize any further damage.

Then you need to dis-assemble the rest of the phone and clean all the affected parts using Isopropyl Alcohol 99%+ (available at electronics parts stores) to remove all traces of corrosion and water. Do not use "rubbing alcohol" as in some cases this is only 70% IPA or less, can contain scents or other additives and is not as effective. If you do use it, check the label to verify the amount of IPA. The higher the percentage of IPA the better

Here is a link that describes the process.

Electronics Water Damage

As always with electronics, especially surface mounted PCBs be gentle when handling and especially when brushing away the corrosion. You do not want to remove any components from the board.

Hopefully after you have done all this the phone might possibly work correctly again.

Here is a link to the ifixit iPhone 6 guides which may be of some help.

If this process seems too daunting, take your phone to a reputable, professional phone repair service, experienced in liquid damage repair and ask for a quote for a repair. If you decide to do this, do it sooner than later.