I don’t know if this is the sub for this but looking at other questions assume it would be a good place for it-

So i have an old iPhone and android that have been off and put away for about 4 years. They’re properly stored in a dry cool environment in my parents house until i get back home. I know the battery can likely be dead from being drained from not being turned on /not charged for so long… i can just take it to get battery replaced but will the memory on the device itself be fine or will they be wiped? Earlier this year i turned on one of my phones that were off for about a year and it was fine. What can i expect from these others?