Chosen Solution
My kid dropped my iPhone 7 from our 3rd story flat a couple of months back. There were a couple of barriers due to which it wasn’t a direct fall. Also, it fell into wet sand. Basically, there was no damage at the time. Nothing visible and the phone had been working fine for past 2 months Last week, the battery drained pretty quick ( in about 4 hours). From that day onwards, no matter what I did, ( reinstall, DFU, fresh install with nothing installed on the phone), the phone discharges in 12/13 hours if left on standby (aeroplane mode, without a SIM or WIFI) and within 2-3 hours of light use. I changed the battery, unfortunately that didn’t help. It still drains in 12-13 hours in standby and 3-4 hours while usage. I am not sure where to go from here, any help would be greatly appreciated. EDIT I switched off the phone last night before going to sleep. Battery at the time was 69%. When I woke up 7 hours later and turned the phone on, it had drained all the way down to 6% ( while it was turned off)
I suspect you are seeing some aftereffects from the fall. How wet was the sand? Just wet and heavy or was there some standing water (puddles)? You either are suffering from latent effects due to water inside the phone or issues regarding some cracked solder balls or other internal physical damage. You could try disconnecting one peripheral at a time to see if the problem goes away (FCAM, RCAM, Button flexes). If nothing helps, then things start pointing towards a logic board issue.
