Arop A , The rice would have done very little to help your phone as it is not a very good at liquid absorption, make sure to clean the rice out of all nooks and cranny's. Stop charging or powering up your device until the liquid damage is addressed correctly, as you could be shorting out components inside the phone. You really should take care of the corrosion that is happening inside the phone from the water damage as that could be your problem. A tear down link for your device Link #1, disassembly guide will enable you to get inside the phone to remove the damage/corrosion caused by the liquid. Use the 2nd link as a guide/instruction on how to clean/repair the device from liquid damage. After this you will be able to power on the phone and see if further damage has to be addressed. Good luck.
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Desmontaje del iPhone 6s Plus
Electronics Water Damage