I recently found an old iPhone 6 and noticed that it wouldn't turn on. At first, it showed the dead battery icon, so I used a portable charger to give it some power since I forgot my charger. Now, when I plug it into a charger, it briefly shows the Apple logo, but then the screen goes black again. I tried resetting it using the power and home buttons, but that didn't work either. The phone looks fine with no external damage. Is there anything else I can try?
1 Answer
It sounds like your battery might need replacing. Apple recommends keeping lithium-ion batteries charged to around 50% if you’re storing devices for a long time. Given that your phone has been off for about 5 years, it’s possible the battery went into a deep discharge state, which can make it unable to hold a charge anymore. You might need to replace the battery to get it working again.

Yikes! If Apple doesn’t sell replacements anymore, have you thought about checking IFixIt? They have batteries for around $30 and people seem to like their guides!